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 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.
A Healer does not last long if she is in the range of an Air Defense, so make sure you destroy the Air Defenses first or otherwise occupy them before sending in your Healer(s). One strategy is to send a few Wall Breakers in to break the wall that is protecting the Air Defense. Then send in a group of Giants (usually 12 or more) to destroy it. The remaining Air Defense can be a problem so be able to use a few more troops to take it out. Finally send in a Healer along with other troops after the Giants. As long as the Healer does not get distracted by other Troops taking damage, or is not killed by an Archer Tower or Wizard Tower, the Giants will live for a significant amount of time (due to the constant healing) and will distract the defenses while the other troops destroy everything. This is known as a Giant-Healer raid and is pretty effective when attacking a Town Hall 6.
If at any point in the battle all of your non-Healer Troops are killed and you have no more non-Healer troops or Lightning Spells/Earthquake Spells to deploy, the battle will end, even if you have Healers deployed that are still alive or non-Lightning/Earthquake Spells that are still in effect.
Healers can allow Giants and other defensive troops to withstand massive amounts of damage, even doubling that of their normal health. Support durable Troops like Giants or P.E.K.K.As with Healers.
As of the December 2015 update, the effect of stacking multiple Healers to heal the same target is reduced. The stacking effectiveness begins to decrease after 4 Healers and decreases drastically after 6 Healers. For this reason, it is not advised to use too many Healers on the same target as the healing efficiency will decrease if they are massed on one target, like the Archer Queen.
Healers do not last long if she is in range of a Single-Target defenses or an Air Defense, so make sure you upgrade and protect your Air Defense as much as possible.
As of the 24 February 2015 update, the strategies to defend against Healers involving Traps placement no longer work, as Healers do not trigger Traps anymore.
Initially, the Healer has long, white angelic wings with short, white hair. She wears a golden dress that ends in 4 long pieces. Her dress has a white 4 sided star.
At level 3, the color of her aura and the color of her dress both turn from light yellow to a bright purple - pink color (Similar to elixir- pink or level six walls).
In the Chinese language setting of the game, the Healer is called "Angel", which the unit resembles.
As part of the 23 May 2013 update, Healers had their training costs reduced at all levels. The training time was shortened from 20 minutes to 15 minutes and the required housing space was lowered from 20 to 14.
You can have a maximum of 17 Healers at one time in a complete set of fully upgraded Army Camps. This number increases to 19 if you include the 2 that can fit into a level 5 or higher Clan Castle. On the battlefield, you can clone an additional 4 Healers with two level 3 or higher Clone Spells.
Note: Having this many Healers is highly discouraged as your Troops will have no offensive capabilities unless you bring Clan Castletroops or Heroes.
Although Healers have no favorite target, as of the September 16, 2014 update, Healers now prioritize healing larger groups of troops.
The Healer requires the least amount of Elixir of any troop to upgrade to maximum level (a total of 5,250,000 from level 1 to 4).
Prior to the September 2014 update, a Healer in a defensive Clan Castle would heal damaged buildings. This is no longer true and she will now only heal Heroes and other Clan CastleTroops when defending; if Heroes and Clan CastleTroops are taken out, she will do nothing for the rest of the defense.
As the Healer has no offensive capabilities, Rage Spells will increase her HPS.
As of the February 24th, 2015 update, Healers no longer trigger air traps or Traps set to air mode.
Part of the May 4th 2016 update, the Healer's training time has been decreased from 15 minutes to 10 minutes.