The Descent

An endless procedural dungeon under Emberhold for level 30, solo or a party of 1-5. Its entrance is a pale silver rift beside the Rift of Ash, in Emberhold's north corner.

How a run works

Every floor is generated from your run's seed and the floor number, so no two runs are alike, and everyone in the party sees the same floor.
Start deep: you may start at any floor up to one past your deepest completed (a party uses its best member's; the others are carried).
Each floor has a safe landing with a choice (a blessing, a curse, or descend at once), 0-4 rolled modifiers, elites with affixes, and a Warden guarding the stair down.
Every 5th floor a named boss from 18 bodies, with generated names and two to four moves, never the same body twice running.
Death ends the run. The fallen watch the rest of the party.
Difficulty is depth alone (plus party size): monster levels climb a little with depth, then their health and damage keep growing.

Depth bands and themes

Band	Floors	Themes
The Shallows	1–5	Ash Halls, Dripping Deeps, The Gnawing Warrens, The Ossuaries
The Ash Halls	6–10	The Ember Sanctum, The Cinder Throat, Ash Halls, The Deep Seam
The Deep	11–20	The Rimeglass Deeps, The Frozen Halls, The Drowned Halls, The Sunken Abbey, The Buried Sun, Dripping Deeps
The Hollow Dark	21–35	The Root-Choked Depths, The Ossuaries, The Molten Rifts, The Frozen Halls, The Gnawing Warrens, The Deep Seam, The Ember Sanctum
The Quiet Reaches	36–∞	Halls Where Nothing Rings, The Hushed Hollows, The Unlit Crypt, The Root-Choked Depths, The Molten Rifts, The Rimeglass Deeps

Modifiers

Each floor rolls up to four of these, shown on the landing.

Feeble: You deal 25% less damage.
Sour Blood: Healing received -25%.
Slow Draught: Potion cooldowns +50%.
Thin Air: Mana regeneration -30%.
Stout Foes: Monsters have 20% more health.
Frenzied: Monsters attack 15% faster.
Crowned Packs: Elites are twice as common.
Volatile: Monsters burst on death (move out of the circle).
Smouldering: Elites leave burning ground behind them.
Rimed Floors: Ice underfoot: you move 10% slower.
Gloom: Darkness: you see less of the floor.
No Rest: No health regeneration out of combat.
Reckless: You deal and take 30% more damage.
Glass: Critical hits +50% damage, maximum health -20%.
The Fading: Monsters fade out of the world and back.
The Hush: Sound stops. Something is listening.
Inversion: The dark turns pale. The light is wrong.

Blessings

Ember Heart: +10% damage dealt.
Iron Skin: -10% damage taken.
Deep Breath: +30% mana regeneration.
Warm Hands: +15% healing received.
Long Wick: +10% maximum health.
Quick Step: +8% move speed.
Keen Eye: +25% critical damage.
Echo Tithe: +25% Echoes of the Deep.

Curses

Optional: a harder next floor for a better reward.

The Deep Toll: Next floor: monsters +35% health and damage. Reward: an extra chest, +60% Echoes.
The Black Candle: Next floor: one more modifier and twice the elites. Reward: +1 item level on its chests, +50% Echoes.

Elites

Elites carry one affix, two past floor 20 and three past 40: Shielded, Hasted, Vampiric, Splitting, Fiery, Frozen.

Rewards

Echoes of the Deep for every floor and boss, spent at the Descent's vendor (character effects: Grave Motes, Pale Moths, Frost Breath, Slow Runes, Torn Pages and potions).
Magic Find grows with every floor while you are down there.
Prismatic gear from floor 5: very rare at first, more likely the deeper you go, and better from bosses than chests. See Prismatic gear.
World-boss uniques from Descent bosses from floor 20.
Ledger milestones and titles the first time you clear floors 5, 10, 15, 25, 35, 50, 75, 100.
Weekly boards in the game: the deepest run, and the fastest deathless runs to floors 10, 25 and 50, solo and in a party.