Regeneration causes unit to regain health at the start of each combat turn, and reduces the chances of them receiving permanent afflictions. Regeneration functions as a % of maxhealth that turn, and can be increased by things that increase or decrease maxhealth, including size-changing and dominion effects for pretenders, prophets, and disciples.
There are three main types of regeneration: inherent, limited, and true. Inherent regeneration is a unit ability for some chassis, such as werewolves. Limited regeneration derives from magical items or spells (e.g., personal regeneration). Sources of limited regeneration do not affect lifeless beings. True regeneration is from an N9 bless, and affects anything that can be blessed. (shrouds, sacred units, prophets, and disciples).