Reward room

A reward room (or "vault") is a special room found on some floors the dungeon.

• The first type of reward room is locked with an iron door. This door can only be opened with a key, located in a key holder room on the same floor. Keys are not interchangeable between iron doors, even on the same floor.
• The second type has no locked door. Instead, access is done through a dangerous vestibule.
• The third type is locked with a special map feature, such as a marble statue, portcullis, or wooden barricade.

Properties

The walls of a vault, including the iron door if there is one, are protected. They cannot be damaged or bypassed in any way, including but not limited to tunneling, burning, teleportation, drinking a Potion of Descent on the previous floor, etc.

The exception is a type of reward room which must be accessed by shattering or tunneling through a marble statue that does not benefit from this protection.

Possible rewards

Reward Room	Description	Min. Depth	Frequency
Mixed Item Library	A room with a number of random items, guaranteed neutral or positive. You can only take one at a time.	1	30
Single Item Category Library	A room with a number of rings or staves, guaranteed positive. You can take only one at a time.	1	15
Apothecary or Archive	A room full of random potions or scrolls. These can be either positive or negative. This includes Scroll of Aggravate Monsters and Scroll of summon monsters.	8	20
Pedestal	A room with one or two items on pedestals. The room can contain: One weapon with a good runic effect. One suit of armour with a good runic effect. Two random Staves (you can take both).	5	30
Outsourced item	A runic weapon or suit of armor inside a key holder instead of key.	5	20
Rare consumables	Two pedestals with Scroll of Enchantment or Potion of Life on each. You can take both.	10	30
Dungeon	Two allies chained up for the taking.	5	12
Kennel	Allies locked in cages in an open room; choose one or two to unlock and take with you.	5	30
Legendary Ally	Approach the altar with the orb to activate a portal and summon a legendary ally.	8	15
Vampire Lair	Allies locked in cages and chained in a hidden room with a vampire in a coffin; vampire has one cage key.	10	5

Note that in every kind of reward room Rings and Wands will have their type (but not bonus) identified as soon as you see them, as of 1.7.1. Staves will have their type and maximum (but not current) number of charges identified. 

This article is related to version 1.7.2 and may be out of date.