A unit that is decaying is aged 5 years per combat round and takes 1 fixed point of damage every other round. This is doubled for units that have the effects of quickness. There is some chance for this effect to end every turn, however it is not well understood. A current estimate suggests that an affected unit has a 5% chance to make a magic resistance check vs 15 every round of active combat to be free of the decay.

Like poison and profuse bleeding, decay will continue to apply its effects to units in the turns following completed combat. It is unclear whether or not the chance for the effect to end still applies during this time.

Better understand the mechanics behind decay ending