Protection

Protection is an effect that lowers your AC but does not involve wearing armor. There are few types of protection:

• The spellbook of protection gives a spell that temporarily lowers AC by 3.
• A +1 ring of protection lowers AC by 1, a +2 ring of protection lowers AC by 2, and so on. Cursed rings of protection tend to increase AC.
• You can attempt to purchase some protection from a priest by donating to a temple. (To donate, #chat with the priest.) The donation must be at least four hundred times ones' experience level, but less than five hundred times. For example, a level 6 character would donate 2400 gold. There is a strategy called the protection racket that makes use of this feature to drastically lower armor class.

These all stack; you can buy protection from a temple (more than once), wear two rings of protection, and zap the spell, if you need a large temporary AC boost.