This deck is centered around the combo of Solitary Confinement + Gibbering Descent.

Here's how it works: You wait until you can untap with 4 mana next turn, and cast Solitary Confinement. Usually it's best to Duress / Inquisition the same turn you're doing this to ensure it resolves, but it's not a necessity. Assuming your opponent doesn't flat-out Disenchant the Confinement, you probably won't have to worry about anything they do. During your next upkeep, when discarding for Solitary Confinement, discard Gibbering Descent and cast it with its Madness cost. You'll be skipping your draw step and discarding two cards every upkeep thereafter, so you should get Hellbent very quickly, if not immediately.

With Gibbering Descent + Solitary Confinement, the following will be true:

-You skip your draw step
-You skip your upkeep
-You have shroud
-Prevent all damage that would be dealt to you
-At the beginning of each opponent's upkeep, that player loses 1 life and discards a card

You don't have to pay Solitary Confinement's upkeep cost if you're skipping your upkeep entirely, so you will stay in this game state, without drawing cards or really being able to do anything except use the cards you have on the table. The sad part is that if the opponent has Naturalize, you're fucked. The good part is that the opponent will die in, on average, 20 turns, barring any lifegain on their part, and you can increase the clock depending on what you have in play.

Enlightened Tutor really helps this combo assemble, too - you can go T4 Confinement + Tutor, ensuring you have the lock. Otherwise, there are other cards to help out either to kill the opponent once the lock is down, to defend while setting up the lock, or to win another way entirely.

The creatures are all very powerful for their costs, but have painful upkeep abilities - which thankfully are negated by Gibbering Descent. The Masticores also provide Madness outlets to discard Descent to. The vanishing creatures (Calciderm especially) just provide pretty resilient bodies for blocking while setting up, or bashing once the lock is down. Masticores can also be tutored with Enlightened Tutor, when the game state would favor their presence.

Luminarch Ascension is just a 1-of because the deck is tight on space (and this can be tutored for), but it's extremely powerful with either the full lock or just Solitary Confinement on board. Confinement lets you stall for turn after turn, building up Quest counters very easily until you can just start flooding the board with 4/4 Angels and winning shortly after.

Because the lock makes you mostly immune to creatures I didn't feel the need to include a ton of removal, but that which I did use is very synergetic - Pillory of the Sleepless drains the opponent every turn, effectively halving the time it takes to kill them while the lock is up. Inquisition can also hit creatures, but I'm not all that afraid of creatures in this deck.

Signet is to help fix mana (on a budget here, as always), and Night's Whisper is because card draw is always strong - esp. when trying to stall out with Confinement, or to find combo pieces or whatever.