nethack - getting protection from any priest at an altar
The recipe is you have to #chat at the priest in the room that has the priest's altar, and have (400 gold coins * Adventurer Experience Level) in open inventory (not in a bag of holding or such).
So, if an Adventurer is XL11, they would need $(( 11 * 400 )) = 4400 gold coins in open inventory to give to the priest.
The priest will then ask for a contribution. Give the full amount per the formula above. Will get a response of wording like "thy contribution as been rewarded," and you should see the Adventurer's armor level (AC) improve.
WARNING: If the Adventurer kills any pets or peaceful creatures, the protection can be rescinded.