Offering rooms are a Room type that contains at least 1 Relic on pedestals, which you can take at the cost of Curses.
If there are more than one Relic offered, only one can be taken.
The cost of the Curses can be doubled with Tariffs.
You may have one of the Relics per free if you drink Freeloader Draught in the room (you can still only pick up one Relic).
The rooms can be found in crawl spaces, or just normally spawned on the floor. When they spawn on the floor normaly, the room will be locked (needs one Key to enter).
Destorying the Relics will not give you the Curse cost.