Health is one of the main element of a Hero or unit card. Whenever a hero or unit enters play, it will have the original maximum health as the card description gives (with an exception of disease). A card is removed from play if the current health of a card reaches zero.
The maximum health of a card can be increased by means of Health Plus, Give and Protect. Heal, Drain, Drainbolt and Regenerate abilities can increase the current health up to maximum health the card currently holds. There is thereotically no way to decrease the maximum health, but the Wound ability effectively prevents most of health restoring abilities on certain victim cards, which counts the ability as the only way to decrease the maximum health.
Cards have initial health of 1 to 10, of which generally higher health cards have higher ready value. The thereotical maximum of health is infinite, which can be achieved by two players, one team using a large number of high-regenerating cards, another side using weak flying units and a large number of Give Health artifacts. The game will eventually reach a point that morale points of both sides crashes because of too many turns taking around.