Altars are places where you worship Gods.
First time you walk over an altar of a god you haven't met yet, you will decipher his or her rituals form the carvings on the altar, enabling you to contact the deity via prayers. The deciphering itself takes no in-game time.
You can kneel and pray on the altar for diminuitive boost to piety, or you can sacrifice items for much higher boost. See the pages of individual deities for their aligned materials and items, granting you even larger amounts of piety.
Altars can be found randomly throughout the dungeons, while certain locations guarantee an altar to appear. An altar can only be generated inside of a room and only one altar per room is possible, making the whole room a temple to the deity. You can only pray to the one god while inside of his temple, but as soon as you leave the temple, the prayers to other gods will become possible once again.
Although finding temples is a question of chance, the game features several fixed, guaranteed altars:
- A valpurium altar of Valpurus in the Cathedral of Attnam
- This particular altar is the only one that cannot be polymorphed
- A basalt altar of Silva in the Crystal Cave
- A steel altar of Cruentus inside of Oree's Lair
- It is possible to polymorph altars. Doing so not anger the aligned deity or count towards the five items per square limit of polypiling, so you can easily place your line of items for polypiling over an altar to get rituals of several new deities.