The Healer is a flying unit. She is the only troop with no attacking/offensive capability, but can heal any ground Troops, except when she is defending as a clan castle troop (in which case she heals damaged Clan Castle reinforcement troops and heroes).
When the Healer is deployed, a pulsating circular aura appears around her. If all units have full health, she will start healing the closest troops (although it will have no effect on the healed troops). Should a ground troop be damaged by a Defense, she will fly over and start healing.
Note that Healers will not heal flying units (other Healers, Dragons, Balloons, Minions, Lava Hounds or itself) unlike a Healing Spell which heals every kind of troop.
Note that Healers will heal Heroes at a reduced rate of only 50% of her normal healing rate; keep this in mind if you want to use Healers with your Heroes.
This is why the all healer and Archer Queen strategy known as a queen walk is less commonly used.
Healers cannot attack at all. They are completely unable to defend themselves, and will totally ignore any enemy buildings or troops attacking them. If they have no target to heal, they will simply remain stationary even if they are taking damage.
Unlike all other troops, healers are measured in (HPS): Heal per second, not in (DPS): Damage per second.
