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 55% of her normal healing rate; keep this in mind if you want to use Healers with your Heroes.
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 healing per second (abbreviated as HPS; stated in-game as "Heal"), rather than in 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, and extremely effective with Town Hall 5 since there is only one Air Defense in this Town Hall level.
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.
A Healer can trigger air traps, including the Seeking Air Mine, so be careful when deploying them. While the Air Bomb will usually not be enough to kill a Healer, the Seeking Air Mine will prove fatal. Skeleton Traps set to air mode can chip away at a Healer if no other troops that can target air are nearby.
A strategy called the Queen Walk is where players place many healers surrounding an Archer Queen or other heroes. This is usually done to take out Air Defense on air attacks.
If you are using an air attack with a Queen Walk, consider first deploying some lesser troops where the Queen will be deployed, such as Balloons, to test for Seeking Air Mines. Not doing so can cause the Healers to be wasted quickly by these Mines which will ruin the Queen Walk.
Rage Spells will increase the Healer's HPS, just like how it increases any other troop's DPS. Doing so can be extremely useful for Queen Walk strategies; this extra HPS can save the Archer Queen from a heavy assault from defenses without having to use her ability.
Healers do not last long if she is in range of Single-Target defenses or an Air Defense, so make sure you upgrade and protect your Air Defense as much as possible.
Since healers take up 14 spaces, it is not recommended to donate for defense her as she does almost nothing on defense and only heals other Clan Castle troops and heroes.
The Healer undergoes significant visual changes at all levels.
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).
At level 4, her aura reverts to yellow but her dress remains unchanged.
At level 5, her aura turns to white and her dress is now light blue. She also wears a light blue headband.
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 20 Healers at one time in a complete set of fully upgraded Army Camps. This number increases to 22 if you include the 2 that can fit into a level 5 or higher Clan Castle. On the battlefield, you can clone an additional 6 Healers with three fully upgraded 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.
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 of the February 24th, 2015 update, Healers no longer trigger air traps or Traps set to air mode. This change was reverted in a balance update on August 25th 2016.
Part of the May 4th 2016 update, the Healer's training time has been decreased from 15 minutes to 10 minutes.
Healers’ heal radius was reduced from 2 tiles to 1.5 tiles as part of the June 18th 2019 Update.
As a result of diminishing effects of additional Healers, the maximum possible healing per second on any troop (barring the use of Rage Spells) is exactly 5 times that of a single Healer's healing per second. For max-level Healers this is equal to 400 HPS, or 220 HPS on Heroes.