Corrosion

An attack that inflicts corrosion
(cor) damage – acids, disintegration
beams, etc. – destroys one point of
the target’s DR per 5 points of basic
damage rolled. This affects armor
first, then natural DR. This reduces
DR against future attacks, not against
the attack that burned off the DR!
Natural DR lost by living beings heals
at the same rate as lost HP.