Stairs take you up or down a level. An upstair on a lower floor will usually be connected to a downstair on a higher floor, and vice versa. Travel through stairs by using the < (up) or > (down) commands. Some branches' stairs work differently (see below for detail).
Using a staircase normally takes 2.5 turns; 1.0 turn in the old location, and 1.5 turns in the new location. Using a stair with an unknown destination (stairs that display a yellow * in tiles; stairs with a white glyph in Console) is "fast"; you spend 0.75 turn in the new location instead. This means that, when descending an unknown staircase, you'll always get a chance to act before monsters do.
Traveling through stairs does not count as movement. Species movement speed doesn't matter, so a Naga takes the same time to use stairs as a Spriggan, and Cheibriados doesn't slow stair travel. Stairs don't count towards the amulet of the acrobat bonus. However, effects that prevent movement (constriction, throwing net, etc.) usually prevent stair travel.
Normally, only the player character will use stairs. Most non-summoned monsters will follow you through stairs if they are adjacent to you.
Using the up staircase on D:1 ends your game. If you've collected the Orb of Zot, you win. Otherwise, you lose, treated as if you have quit the game. If you don't have the Orb, the game will ask for a confirmation before leaving.
Each floor within a branch normally contains three up staircases and three down staircases. Traveling between branches is restricted to a single staircase ("branch entrance" / "branch exit"). Branch entrances look different from regular stairs, but are otherwise identical.
In addition, floors may also contain escape hatches, which function as one-way staircases and are a different color than normal staircases. Also of note are shafts, a type of trap which can drop you 1-3 floors.
Vault wardens may cast the Seal Doors spell to seal all staircases and doors within range. Such staircases are impassable until the seal is lifted, either after enough time has passed or the caster has been killed.
Instead of regular stairs, the Abyss has one-way Abyssal Stairs leading deeper into the Abyss. These are generated randomly or after the player has gained a certain amount of experience. There are no up-staircases in the Abyss -- only exits leading back out. These exits are randomly generated, becoming more common in the deeper layers of the Abyss and are much more common once you have collected the Abyssal Rune; exits may also be generated after killing enough monsters.
In the Hell branches (Gehenna, Cocytus, Tartarus, and the Iron City of Dis), there are only 1 set of stairs, except on the final level. And, instead of staircases up, there are portals out, which immediately take the player back to the Vestibule of Hell; these portals serve as the destinations for the staircases down from the previous floor.
In Pandemonium, each floor can only be visited once. Each floor at least three "gates to another region of Pandemonium" - these one-way stairs will send you to a new floor, at a completely random location.
You may find direct exits out of the Pandemonium, but these are rare; each rune you collect in Pandemonium makes it more likely to spawn. More common are "exits through the horrors of the Abyss", which lead to the Abyss and will return players to the Dungeon after they find an exit from the Abyss.
The Tomb of the Ancients has cursed one-way staircases instead of regular stairs, which force players to locate another staircase to return to a previous area instead of simply heading back up the stairs they came down. Additionally, there are not always three stairs up and three stairs down on each floor of the Tomb. See The Tomb article for more details.
Stairs are one of the most important escape tools in Crawl... so long as the destination is safe. In 1 turn, an upstair lets you escape from (non-adjacent) monsters below, rest, and recover from status effects. If you've left a dangerous enemy behind, you can enter from another downstair, which will often be in a new part of the level. The lack of easily accessible stairs is what makes shafts and teleport traps so dangerous.
They also allow for stair dancing. Since only adjacent monsters follow you up, stairs can be used to split groups of monsters. There's a huge difference between "fighting 2 orcs, resting, and fighting 3 orcs", and "fighting all 5 orcs at once". Also, going up to a cleared level makes it very unlikely for you to encounter new monsters during a fight. Some monsters (derived undead, Geryon, the Royal Jelly...) won't follow you up stairs, for better and worse.
However, stairs are not infallible:
- Stairs give adjacent enemies 2.5 turns to hit you, and non-adjacent enemies get 1 turn. If you're at low HP, you can die as you go through a stairs. In addition, not all monsters are safe to stairdance. For instance, an ogre or hydra can outright kill you if you give it 2.5 turns of attacks.
- Certain effects can move you off the stairs, interrupting travel. For example, elephants and dragons can trample on attack, pushing you off. Dispersal traps can be activated by enemies, blinking you away.
- Most statuses which prevent you from moving also prevent use of stairs. Being inflicted by sleep, paralysis, etc. will interrupt all actions, forcing you to go up again. Confusion gives a 50% chance to fail going upstairs. Stuck and Tree Form prevent movement, too.
Overall, stairs are an extremely powerful tool, but there are some situations where they are dangerous.
Tips & Tricks
- Optimal exploration is, in broad terms, moving to the tile that's closest to the upstairs. Whether you are 7 or 8 tiles away from an upstair can be the difference between escaping a D:2 adder and not. (This type of exploration is not required to win the game. There are also considerations like dungeon layout and traps.)
- Most levels have 3 sets of normal stairs. If you don't think you've fully explored a floor, you can use the minimap (or press X then > or < to cycle through up/down stairs respectively) to count the amount of normal up/down staircases you found. Branch entrances, portals, and escape hatches don't count towards the count of 3 stairs.
- If you see less than three of each, some hidden area of the floor is walled off from the area you're in. The best way to reach it is to exit the floor and then reenter through an unexplored staircase on the floor above or below.
- "Triple visitation" is the strategy of visiting all 3 downstairs to know their location. This makes the level safer if you are teleported away, and knowing multiple stairs can be useful in a dangerous situation. However, this always poses a risk. Every stair you take has a tiny, but non-zero chance of being fatal. For instance, a stair that's next to Sigmund or Grinder can kill you with almost no counterplay.
- Downstairs aren't much different from upstairs - they can be used to the same effect. Since the floor below is unexplored (and often more dangerous), a downstair is naturally risky. But there are situations where going down is relatively safe. For example, if you are shafted, when you go up, you'll know if the stair below has monsters waiting. If the floor below is unexplored, beware of noise, which can attract new monsters.
- Prior to 0.29, stairs would only be "fast" when entering a new level; not all unknown staircases were fast.
- Prior to 0.28, the Hells had the usual 3 sets of stairs on each level.
- Prior to 0.22, player ghosts couldn't use stairs.
- Prior to 0.21, monsters spawned over time on floors in the main dungeon as well as on level generation. Sometimes, these monsters could be spawned from stairs, and if the staircase was to a different branch, this could lead to monsters from other branches spawning in your current branch. (This had the potential to generate some fairly scary encounters, such as finding an azure jelly in the Lair.)
- Prior to 0.20, The Tomb had normal staircases instead of one-way stairs.
- Prior to 0.16, stair mimics could be found, which would then fight the player when discovered.
- Prior to 0.13, each branch connected to the Dungeon and the Lair had three exit staircases, in spite of the fact that they only had one entrance.