Priests are the first purchasable reinforcement bought at your citadel. Other versions of this unit can be summoned by generals via idols. They cast a heal spell every five seconds on allied units. Priests will target nearby injured demigods over reinforcements or minions, but otherwise heal indiscriminately. Although they are not combat units, they are relatively tough and have a strong, short ranged attack.
A unit healed by a priest unit get's an 8 second marker, preventing them from being healed by other priest units again while the marker is active. This means you can get healed every 8 seconds at best.
Priests in range of an allied Sedna with Healing Wind 2 have enhanced healing abilities.