Timelord Thoughts 11 - Heaven Sent

A story featuring just the Doctor in a head-spinning clockwork puzzle trap.  It's also the episode that has taken me the longest to write about (sorry about that). I wonder if that's an indication of the quality of :

Heaven Sent

• The opening monologue from the Doctor is obviously about the fact that Death is stalking towards us from the moment we are born. It's not so much the words that captivate me as the images and sounds that accompany them. The bright sunlight through windows onto cold hard stone, The orange glowing cogs. The bloody marks of the passageway floor. The music transforming from sounding like something our of a spaghetti western into a classical piece as we approach the central chamber and the hand pulling the lever and turning to dust. From the offset I can tell that this is going to be something special.
• Don't the struts holding up the teleport chamber look very like the girders from the Eighth Doctor's console room in the TARDIS?
• "I am the Doctor. I'm coming to find you, and I will never, ever stop". This is one pissed off Timelord. Remember those words.
• The castle setting with the TV screens and who knows what terrors and traps within reminds me of the game show "Fort Boyard". As well as ex-Eastender Leslie Grantham, the show featured Doctor Who gust star Geoffrey Balydon - and in series 5 a certain Mr Tom Baker.
• I  know it's a necessity to get dialogue into an episode featuring only one actor, but I totally buy that the Doctor would talk out loud to the enemies he knows must be listening.
• The spade covered in dried earth. Our first clue, But who put it there?
• Who knew that the Doctor hate's gardening? His first incarnation loved pottering about in that big place we saw in "The Five Doctors". 
• It clear that this regeneration is very impatient and I don't blame him -  "I just watched my best friend die in agony. My day can't get any worse. Let's see what we can do about yours!"
• You can just some writing on the far right wall - and it's the text of the Doctor' opening monologue. Which begs the question - who wrote it there? Is it some kind of instruction manual for the trap?

• The moment the Doctor realises that the TV screens show a view of him, that "something" is watching him and then he spots the hooded figure - I've got goosebumps. (I'm going the refer to the creature as "The Veil" from now on as that's what it's called in the credits if not on-screen.)
• A fly on a video screen. Another homage to "The Ring" maybe?
• The Doctor looks genuinely scared as he runs up the corridor looking left and right for a way out.
• "Back when I was young and telepathic". Seems he has lost those abilities in the 1,100 years since he was the Tenth  / Eleventh Doctor.
• If doors are always cross that might explain why I keep bumping into the frames when I walk through them. Poor spatial awareness you say? No, the doors just don't like me. This one does seem to like the Doctor though.
• "I've finally run out of corridor. There's a life summed up". Brilliant line.
• "I'm actually scared of dying" - and everything stops. Frozen in time. Flicking flies out of the air like Quicksilver from the X-Men / Avengers movies. Or a million other films, TV shows and video games. It's still a great image.

• Likewise the revolving levels of the castle look wonderful. This trap is not Fort Boyard - it's the classic puzzle game "Myst". Maybe all those gears and cogs on the opening titles meant more than just parts of a clock?
• It's a very nice room. It would get full marks on "Four In A Bed" if it wasn't part of a deadly trap.
• The peeling painting of Clara gets a sad smile from the Doctor as he examines it. But who painted it and put the eyeglass there for him to find.?
• Cleverly Moffat and director Rachel Talaly are using what they have told the audience to great effect. We've been told that what the The Veil sees appears on the monitors, so when an image of the Doctor in from of the painting appears, we *know* that its close, and that makes it all the scarier.
• That's some very Peter Davison era synth music from Murray Gold, which fits perfectly as the monster shuffles its way forward in the background. it reminds me of some of those 80s horror movies I used to watch.
• What an odd childhood the Doctor must have had if he was exposed to dead old ladies covered in veils and flies. The "pop" he does with his mouth when telling this tale is *very* Tom Baker.
• As is waving a 'gladioli' in front of a creeping monster while prancing about like a cross between W.C. Fields and Dame Edna.
• Okay. No I didn't see that dive coming. Is this all in the Doctor's head? Or is it in some virtual reality illusion? In any case it's a bloody long way down.
• Huh? So we're in the TARDIS now? Or are we?
• "Rule one of dying - don't". I can get behind that.
• So a "storm room" is the Doctor's version of Sherlock's "mind palace" - only this one comes complete with it's own mute version of Clara that never looks at you. Of course Sherlock Holmes is far from the first person real or fictional to use this technique.  It actually dates back all the way to Ancient Rome and Greece. I first came across it in the novel "Little Big" by John Crowley but more famous literary uses have been in novels by Thomas Harris (creator of the evil Hannibal Lecter) and Stephen King (in "Dreamcatcher"). On television it was discussed  by "Connections" presenter James Burke in his follow up series "The Day The Universe Changed" and various police procedurals such as "The Mentalist" and "Criminal Minds" have characters that utilise the method. Showman extraordinaire, all round genius and personal hero Derren Brown is also an expert (watch "Tricks Of The Mind" or any of his live shows to see what I mean.
• The fact that Clara is there is the storm room and the Doctor is compelled to explain how he survives the fall is not only a clever way of showing us how the Doctor thinks, it's also a manifestation of his grief.
• "Assume you're going to survive! Always assume that!". This echoes Clara's line in "The Witch's Familiar" when she tells Missy that the Doctor always assumes he is going to win, he just has to find out how.
• The grimace as he climbs the TARDIS steps. "I can't wait to hear what I say. I'm nothing without an audience". The sly look into camera. The fourth wall just shuddered ever so slightly...

• The part where the Doctor explains that all the things he did before jumping out the window were part of his plan is *very* Sherlock Holmes - specifically the Guy Ritchie films starring Robert Downey Jr. In those there were several sequences where time was slowed down to show Holmes anticipating his opponents moves ten steps ahead. "Am I spoiling the magic?" No, not at all Doctor.
• The lights slowly coming on around the TARDIS control room as the Doctor regains some form of conciousness is just lovely.
• Another great example of there not being a need to show us things. Just the sound of chalk on a blackboard and the questions being there is enough. "Clara" is the Doctor's mind refusing to give up and still wanting the answer to questions even as he lies drowning.
• Just how many skulls are down there? How many people have been killed by this trap?
• Notice how the music changes as soon as the Doctor re-enters the castle. Again it's more classical and majestic. The hero regaining his strength.
• Someone put that dry set of clothes in front of the fire (and lit the fire too). An exact match for what the Doctor is wearing too. Curiouser and curiouser. It's at this point that I'm starting to suspect that there might be some kind of time-related shenanigans going on.

• What do the arrows pointing to the circle of dust mean? Ashes to ashes, dust to dust...? "I will show you fear in a handful of dust" from the Sandman comic - the master of dreams? Is it late and I'm getting tired?
• Yes Doctor, you are the mouse in a very large automated haunted mansion but with a scary ghost that can kill you. The question is why? More questions than answers so far, but I'm utterly gripped by this. Someone has been reading the blog and found out how much I like puzzle movies...
• "Must be Christmas". That grin means business.
• Now we are definitely in horror movie territory. The dark corridors. The dripping water. The creaking door. The squealing violins. The steam rising from plants in a garden that probably reeks of death and decay. Don't go in Doctor - too late!
• Ah so the arrows and the hexagon above mirror the garden and it's paths below. With what looks like a grave at it's heart. Does the tinkle of bells in the background also mirror the Victorian custom of putting bells in a casket in case the deceased was accidentally buried alive?
• The Doctor's acknowledgement that doing what he would do is what got Clara killed is tinged with such sadness. He blames himself. He knows that he could have - should have - done something to prevent it.
• Is persuading him to dig the grave another delaying tactic to get the Doctor to stay in one place so that The Veil can get him?
• Okay so when the Doctor opens the door and The Veil is right behind, it I literally jumped out of my chair. Even when watching it a second time and knowing it was coming it still made me start. I'm such a wuss.
• Time for another McCoy call back I think - and The Veil struggling to get through the door brings to mind "Curse of Fenric"...

• Just where is The Veil lumbering off to and how will it get the Doctor? It seems to have gone back to the store room. Personally I would not have removed that spade from the door until I was sure it was miles away and even then I'd be checking the screen every five mutes. I guess the flies act as a kind of early warning system so that the Doctor can continue to dig into the golden twilight. But why are the constellations different to what he expected if he has only travelled one light year? Maybe this isn't real space.
• "I Am In 12". Click. The pieces start to fit. That's written on the stone tile from the room with the saucepans. The arrows were highlighting that it was missing and that the Doctor had to find it. Question is - Who took that tile from the store room, wrote on it and buried it in the pit? The same person who left the spare set of clothes next to the fire? Is there another Doctor running around the castle somewhere? Also does 12 refer to the Twelfth Doctor, or 12 hours on a clock or a clue that this is all inside his own head? I'm really enjoying trying to figure all this out.
• Does "I am In 12" have an even wider significance? After all it was buried in The Veil's Yard. See? Valeyard? No? Oh please yourselves...
• Another damn jump as The Veil breaks through the bottom of the pit (I assume it tunnelled it's way through from the other side - wherever that is). I don't think I can take many more scares like that.
• Back to the "mind TARDIS" to try and get out of the latest situation and the Doctor realises he is being terrorised and interrogated. Someone wants his deepest darkest secrets - and this time his name will not do. I'm betting it's information about the Hybrid they want.
• That wide shot of the TARDIS control room is just stunning.

• I don't think it's a huge controversial revisionist leap to reveal that the Doctor originally left Gallifrey because he was scared of something. We've already had a solution to the regeneration limit (and *that* was only introduced thirteen years into the Classic series), and a "hidden " regeneration which didn't call himself the Doctor. This is minor in comparison (at least so far). It depends if they are going to retcon him knowing about the Daleks before he left. That might be a step too far.
• So every time the Doctor confesses a secret, he completes a level of the "game" and the castle levels rotate and new pathways and rooms are accessible. I think this is where the Doctor realises the scale of his trap and that there is no normal way off his floating prison.
• The rise and fall of those two submerged skulls is important - I just haven't figured out how yet.
• "The day you lose someone isn't the worst. At least you've got something to do. It's all the days they stay dead".It's a beautiful summation of the feelings of loss and grief after someone has gone from your life and this world forever. Is this one of the reasons why the Doctor never stands still? 
• Talking of which, it seems he has only 82 minutes to run through what appears to be a series of ever more exquisitely decorated rooms before The Veil catches up with him. This episode is benefiting hugely from being filmed on location. I really want to visit Cardiff and Caerphilly castles now.
• I recall that when the Doctor was hunting for the trap street in "Face The Raven", he told a little boy to "...remember 82". I wonder if that was just a little Easter Egg for the obsessively observant?
• As the Doctor starts to map the castle in his notebook and talk through his observations with "Clara", we can see the beginnings of a theory building up. Hundreds of rooms and corridors, not all accessible at the same time. Rooms that reset themselves if you leave them long enough. Pits fill in, Flowers re-pot themselves. It's like multiple circles of the Doctor's own personal eternal hell, where nothing he does ultimately has any effect - or does it?
• The light filtering through the window as the Doctor sits eating his meal is just sublime. They really have pulled out all the stops to make this episode look extra special.

• "I'm not scared of Hell. It's just Heaven for bad people". Trust the Doctor to have a different viewpoint to us mere mortals.
• Back in the teleport room the Doctor discovers a skull connected to the control panel. It's another important clue. Is it related to the other skulls in the ocean surrounding the castle? Whose skull is it? I'm beginning to put together my own theory involving time travel and a closed loop...
• Then in amongst all the Doctor's musings on the nature of birth and death, they throw the word "bird" into the mix. What's that got to do with anything? Is it a reference to the raven from last week's episode? I'm back to being confused again but I don't care. This is just too good.
• So if The Veil stops and the castle rotates every time the Doctor reveals a secret, what made the door behind the teleporter open? Was it the word "bird" or did the Doctor just get close enough to trigger something for the first time? Then again the Doctor has already said that he knows the castle wants him to solve it's secrets.
• Putting the skull on the edge like that, why it could easily fall off into the water...
• Finally Room 12 reveals itself and it's just another blocked entrance. The game isn't over yet - something more needs to happen before the Doctor can gain access.
• That cross fade from the Doctor's face to the skull confirms it - the skull *is* the Doctor's (however I don't think he has realised it yet). It matches perfectly. Which means there must have been thousands of time loops in the trap before this point, each one ending with the Doctor's death. But why was this skull in the teleport room?
• "It's a trap...I've been following breadcrumbs...this is somebody's game and I can't stop playing". The Doctor sounds very despondent right about now.
• So two days must now have passed since the Doctor arrived - we've seen two sunsets and two night skies. Skies in which the stars are all wrong.
• F***k ! Behind you Doctor! I'm almost shouting at the screen at this point. It's edge of your seat stuff.
• How can he be 7,000 years in the future without time travelling? Are the stars lying? Is this all some macabre "Truman Show"-like entertainment dome with a painted starscape?
• Phew! Another "confession" (hang on a minute...) stops The Veil just in time. This time it's the tale of the Hybrid, but with added commentary.
• "The Time Lords knew it was coming, like a storm on the wind". An "Oncoming Storm" maybe? Like the one in the legends of Skaro? My theory of who the Hybrid is may just have taken a tiny shuffle forward.
• And as the Doctor confesses he knows who, what and where the Hybrid is, the castle shudders and The Veil turns away. We know what that means by now - the door to Room 12 is finally open.
• The skull falls off the parapet into the waters to join it's identical cousins. That must mean that this sequence of events has happened many, many, many times before.
• The music as the Doctor creeps down the darkened corridor towards the shimmering light is almost religious or funereal. At first I thought it was a curtain of light but it's one final opaque wall with "Home" stencilled on it (which fades as the Doctor approaches). The builders of the trap have a twisted sense of humour.

• Nor are they going to make it easy to get through since it's composed of Azbantium - four hundred time harder then diamond and twenty feet thick. It's going to take a miracle.
• And with the camera performing the infamous Dolly Zoom effect (where the camera pulls away while the lens zooms in) a horrifying realisation appears on the Doctor's face. He knows what he has to do and it's so terrible that he retreats into his memory palace TARDIS.
• "That's when I remember...always then..exactly then...why can't I just lose?". Snap! Like clockwork another puzzle piece snaps into place. The Doctor hasn't just come to this conclusion once, He's been in this exact scenario before. Many. many times before. 
• The truth shakes him to his core and he desperately wants to just give in. Have we ever seen a Doctor this low before? But "Clara" won't let him stop fighting - his own brain won't let him. Even though at this point he now remembers all the times he's been round the maze before like a hamster in a wheel. Even though it appears to be utterly hopeless. That's what makes him the Doctor.
• And now there is nowhere to run anyway. Only that final confession will save the Doctor now. The Veil is in room 12 and there is no way out. Is there?
• "Whatever I do, you still won't be there". At his lowest ebb the Doctor's grief at losing Clara overwhelms him. It's heartbreaking and beautifully played by Capaldi.

• Finally his "Clara memory" speaks. "Get up off your arse...and win". Having Clara there as a constant companion in the Doctor's memory but always silent makes this moment much more effective than if she had been talking to him all along.
• Errr.. then again maybe he has been driven mad. Punching the azbantium wall like that must be agony but the Doctor seems determined to get out and punish those that put him in this trap. Just how is this going to help? 
• Slowly my pudding brain slots things together. A closed time loop. The second set of clothes. All the skulls. Surely they don't mean to....?
• "The Brother Grimm. Lovely fellas...they're on my darts team". Even this close to certain death the Doctor can joke.
• "The Shepherd Boy" tale is a short one in which a king asks the titular boy three fundamental questions of life, one of which is how many seconds of time there are in eternity... *
• Six punches. That's all the Doctor gets before The Veil catches up with him. It looks like a hideous painful death. And with that The Veil is gone, its task complete. The Doctor is dead (I don't believe that for a minute - we still have more than ten minutes to go).
• The storm room TARDIS lights flicker on and that familiar hum rises in the background. It's not a new thing to state that Time Lords can take a long time to die - the Tenth Doctor managed to hold off his regeneration long enough to visit every single one of his old companions (and set Captain Jack up on a date), so it's not a stretch to have this mortally wounded Doctor at the cusp of death for ages.
• "They know not to bury us early". That harkens back to the bells and my comment about Victorians being worried about being buried alive. Maybe I was on to something.
• It's going to take the Doctor a day and a half to die and he's not going to waste a single moment of it. Even this close to death he is looking for a way to win. Scarred, burnt and bloodied he drags himself up the tower stairs and through the corridors. Now we know where the blood came from at the top of the episode.

• I was right. Every skull at the bottom of the sea belongs to another version of the Doctor. It's an eternal trap which he is destined to repeat over and over and over forever - designed to torture him to the point where he has to give up the secrets of the Hybrid. Someone must hate the Doctor very much (or fear him even more).
• I was also wrong. It's not a time loop. Time is moving normally which means that based on his comment at the top of the tower, the Doctor (or a version of him) has been here seven thousand years already - and every time he gets to the glass wall in room 12 he figures out what is going on and how many times he must have been here before. It's truly a living hell and it would drive a normal person insane. 
• The hand we saw at the start? That was the Doctor. The only question left is quite how this one dies and another appears.
• It's a great analogy to compare teleporters to 3D printers. As much as you can apply real-world science to a totally impossible device, I've always thought that they must destroy your original body at the departure point and create a new one out of surrounding atoms at the arrival site.
• The Doctor says that all the rooms reset back to their original state when he first arrived. I don't think that quite holds true - this trap is more sophisticated than that, more cunning.
• If he has been here for 7,000 years and each "reset" lasts for three and a half days (we saw two night skies plus a day and a half to get back to the teleport room) then there have already been over 730,000 versions of the Doctor. Probably more as some will have been caught by The Veil quicker - and like this one they all failed to escape.
• As the Doctor burns (trust Moffat to give away the biggest clue at the very start of the episode) the clockwork turns and the teleporter fires up. Just a few fleeting moments left to write "Bird" in the dust of his previous selves. What *does* it mean?
• The cycle begins again with a new arrival. A new, old Doctor. Destined to repeat the actions of the last?
• "I am the Doctor. I'm coming to find you, and I will never, ever stop". And boy does he mean it.
• It's difficult to explain how astonished I am at the incredible montage that follows.Over and over and over the Doctor arrives, escapes The Veil out the window, changes his clothes, digs the pit, reaches Room 12, punches the wall a few times before being caught in the clutches of his worst nightmare. Drags himself back to the teleport room to try again. And again. And again. Seven thousand years. Twelve thousand years. Six hundred thousand years. Each time the Doctor tells a little more of the story of the Shepherd boy and each time a miniscule amount of the azbantium wall gives way. I keep expecting it to stop, but it doesn't. The sequence goes on and on and my jaw hangs open at the sheer audacity of it. One million, two hundred thousand years. Two million years. Is that a hole in the wall? Twenty million years. It's a masterclass in editing, the cycle repeating through the millennia. Now it's a definite corridor through the shining barrier. And still we go on. Fifty two million years. I'm holding my breath. How much longer? The story of the bird is being revealed word by word, step by step.  Faster and faster and faster. It's a blur but I know each action, each outcome. A billion years. More. Deeper into the wall. Closer to escape. Two billion years. Murray Gold makes up for everything else this season with an epic score. It's perfect. It's awe inspiring. "I will never ever stop". And then...
• After four and a half minutes of frankly astounding television the Doctor breaks free and The Veil dissolves into nothing more than rags and clockwork and cogs. I start to breathe again. What now?
• "Personally I think that's a hell of a bird". I think that's a hell of a f***ing Time Lord !!
• He was inside the damn Confession Dial all along ! I think part of me subconsciously guessed that, but wasn't sure until the Dial closes up over the castle. There is only one race that could put so much inside a tiny disc of metal. Which means the Time Lords were the Doctor's jailers. Another part of my theory must be right.
• The Dial might be in it's own Bootstrap Paradox though. The Doctor has it at the start of the series, gives it to Missy for some reason then gets it back, He  hands it to Ashildr in "Face The Raven" and now it's in the middle of the desert. Where did it come from in the first place? There's still one episode left to go...

• "I came the long way round". A deliberate callback to the last line of "The Day of the Doctor" - but I bet he never expected that it would be a two billion year year long journey.
• The Capitol dome rises out of the desert, pristine and shining. Is this before or after the Time War?
• If what the Doctor says is the truth then the final part of my theory was correct too. "The Hybrid is me". **
• We're back on Gallifrey - and there's going to be hell to pay...

Conclusion:

Moffat does it again. Consistently he writes the most original, intricate, bold, format-busting, confusing, twisty and downright amazing episodes of Doctor Who. Words fail me. It's a stone cold classic and the first time I finished watching I could hardly speak. It's Peter Capaldi's finest hour and he's finally and irrecoverably won me over.

The Veil was bloody terrifying for something so simple - made more so by the Doctor's obvious fear of it. The mechanical castle trap was wonderfully realised both in location and set form - full of atmosphere and beautiful designs .On occasion the shot composition was almost painterly. Rachel Talalay and Michael Pickwoad deserve as much kudos as Mr. Capaldi.

The concepts littered throughout this whole series have been preparing us for this episode. The broom that is still the same broom even if the head and the shaft are replaced. The bootstrap paradox. Who wrote Beethoven's symphonies. Ripples in time. Forget the Hybrid - this was the real series arc. Even the supposed talking to the camera turns out just to be the Doctor in his "storm room".

Yes the story does show it's influences. Off the top of my head I can name Moon, Cube, Triangle, Bill & Ted's Excellent Adventure / Bogus Journey, The Prisoner, Groundhog Day, The Shawshank Redemption (just about), The Avengers: "The House That Jack Built", Sherlock (of course), The Prestige, It Follows (funny that I'd only watched that a week before), Dark City, Myst (I mentioned it earlier), the Dark Tower novels. The list goes on.

Let's not forget our Greek mythology lesson. It's the story of Tantalus. He became one of the residents of the deepest part of Tartarus, the Greek Underworld. He was condemned there for stealing the ambrosia of the gods and revealing their secrets when he was taken to Olympus by Zeus. Tantalus's punishment was to stand in a pool of water beneath a fruit tree. Whenever he reached for the fruit, the branches moved out of the way. Whenever he bent down for a drink, the water receded. Eternal temptation without satisfaction (the origin of the word 'tantalise').

Let's talk about the score. Murray Gold didn't produce inappropriate incidental music this week. He didn't even produce something as good as "Doomsday". He surpassed himself and created a whole superb music suite. Totally unexpected and beautiful to listen to. It even used themes and motifs from Beethoven to link back to earlier in the series.

It's difficult to know what to say overall without gushing superlatives. Of course it's not without it's minor flaws and unanswered questions and some of the in-story logic doesn't quite make sense (would you expect anything less from Steven Moffat) but those things are far outweighed by the cleverness of the story and the way it was told, the towering performance of the lead actor and the quality of the direction and (not forgetting) the editing. Some will decry it as "too complicated" or "not for the kids". I don't care. I wouldn't want to see an episode like this every week (nor do I think you could repeat it's style) but this ticked all the boxes for me. It's high in my personal top ten of all time favourite episodes. So there.

God I can't wait for next Saturday

As an extra, and for a bit of fun, let's look at some of those unanswered or unclear questions:

• Who painted the picture of Clara? 
• Who put the eyeglass on the mantelpiece?
• Who drew the arrows pointing to the flagstone?
• Who dug the grave in the first place and put the flagstone in the bottom with "I am in 12" written on it?
• Who put the dirty shovel near the teleport room?

It's all part of the trap to get the Doctor to make his confessions. The painting was there to twist the knife into the Doctor's grief and his guilt at his part in Clara's death. Similarly the eye piece to make him examine it so he would be distracted from the slow arrival of The Veil. The arrows were in the storeroom to get him to look for the flagstone. The shovel was there to get him to dig. The flagstone was under the ground with it's cryptic message to get him to figure out the rooms all had numbers and look for room 12. Ashildr said that the Doctor could never resist a good mystery. The abzbantium wall was meant to be the final barrier, at which point the Doctor was meant to realise the futility of his existence and give up all his secrets. They never planned on him hitting the wall with his bare fists for two billion years.

• Who put the clothes there for the Doctor to find? Why didn't they reset like everything else?

It could have been the Time Lords, but then they wouldn't have known the Doctor would dive into the sea to escape The Veil. I like to think that the first iteration of the Doctor took his clothes off and carried out the rest of the cycle in his undergarments (complete with question mark underpants). Because the Doctor left them there, they stayed there. Part of him was always in that room I think.

• So how do you explain the Doctor's skull and the word "bird"?

Ah, well the rooms only reset when the Doctor leaves - and apart from the point when he picks up the skull and the word gets blown away by the draft, there is always a version of the Doctor in the teleport room, either dead or alive.

• With each version of the Doctor, does he use the same confessions or does he have to come up with new ones? 

The Doctor probably used the same ones, as they were new to that iteration. 

• What happened to the untold number of Doctor skulls dropped  into the sea over the course of two billion years?

It's a Time Lord trap using TARDIS technology. Therefore it's an infinite ocean that never fills up. Or the skulls turn to dust eventually. Or they wash further out to sea. They don't reset because they are outside the castle. Take your pick.

• Why does he use his fist to punch the wall?

When the Doctor enters Room 12 it's in a bit of a rush and he hasn't any other implements (like the spade) with him. Then The Veil blocks the entrance and there is no way out. What about the sonic shades? Errr.... well maybe they don't work on abzantium.

• Why doesn't the wall reset each time? 

It doesn't need to. The Time Lords planned it as the final trap from which there was no escape. The designers thought he would only arrive in the last room once, succumb to despair and reveal everything in order to escape.

Does any of this matter? The thing is, we can all come up with our own answers. It's fun to try. Even without them the episode is still incredible.

I'm incredibly late with this I know, but at least I've only got just over a day to wait for "Hell Bent" !

* The boy replies "In Lower Pomerania is the Diamond Mountain, which is two miles and a half high, two miles and a half wide, and two miles and a half in depth; every hundred years a little bird comes and sharpens its beak on it, and when the whole mountain is worn away by this, then the first second of eternity will be over.".

** Unless of course he means "It's ME", in which case i will be VERY disappointed. ***

*** Then again if it's all about being half-human on his mother's side I owe someone a pint...