Altars serve several different functions as parts of dungeon features:
- Any Key Holder where the key is not held by a monster will have the key placed on an altar. If the Key Holder is based around surviving after getting the key (as opposed to reaching it in the first place) picking up the Key will trigger some kind of dangerous event. The altar may retract into the ground.
- Altars will occasionally hold a semi-id'd piece of runic equipment instead of a key, and will be secluded in locked-off rooms or present in the same Key Holder Machines as a key-bearing altar would.
- In Reward Rooms where you are only allowed to take one item at a time, the items will lie on altars with cages above that lower when an item is taken.
- In locked vaults on higher levels (Brogue 1.7.4 onwards), you may find a pair of Commutation Altars, or a Resurrection Altar.
- In the "legendary ally" reward room, the slot for the summoning orb to be placed in is described as an altar. It has a visible hole in the middle for inserting the orb, unlike other altars. Approaching the altar will automatically insert the orb, and a legendary ally will arrive from the stone archway in the room.
Altars are always "candle-lit", and as such will illuminate anything in a 2-3 tile radius. The reason for the varying radius is that the candles "flicker"... if you are within two tiles of the altar, you always be lit, but if you stand 3 tiles away, each turn you remain at that radius there is a chance that you will be lit for that turn.
Altars are unaffected by Potions of Descent, as is any item that is present on them. If the rogue or any other mob is standing on one, however, they will fall to the next floor regardless.