Every 7.5 seconds, the Witch will passively summon a group of three Skeletons. The Witch's Skeletons are 5 levels higher than her.
The Witch should be placed far behind high hitpoints troops such as the Giant so that she can have enough time to summon her Skeletons and provide offensive support. If the opponent has a Giant backed up by a Witch, wait for the Witch to cross the river. When she does, place some Barbarians, a Baby Dragon, or any other high hitpoint troop right on top of her so they will clear the Witch and turn around to fight the Giant. Remember never to ignore the Giant, as he can deal significant damage to your tower.
The Witch's Skeletons can be taken out easily. Make sure you have a group of distracting troops to keep the Witch from being targeted.
Although the Witch deals less damage than the Wizard, she is more reliable on defense due to her Skeletons. This allows her to distract threats like the Prince, whereas the Wizard would not be able to. However, the Wizard is still better suited for air troops, such as Balloon, as he deals a lot of damage. The Witch's Skeletons may briefly distract other troops, but they are completely useless against the Balloon (or any building-targeting air troop).
It is not recommended to spawn the Witch (or any troop) next to the player's Crown Tower if the opponent has cards like the Rocket or Lightning since they can take out the Witch and damage the Crown Tower at the same time. A Fireball at least 5 levels higher than a Witch can take her out completely.
When using the Rocket to take out a Witch, be careful with the placement because the Rocket is slow. Put the Rocket some space ahead of where the Witch is going to make sure it gets there in time. Note that killing the Witch is a negative Elixir trade since she costs 5 Elixir and the Rocket costs 6 Elixir.
Witches are also useful against slow attacking troops. Her Skeletons can distract troops like a Prince whilst the Crown Towers and/or the Witch attacks it.
Witches can also be used to counter swarms. Her ranged area damage makes her a good choice against low hitpoint hordes. She is very good against incoming Minion Hordes and Skeleton Armies, as she can three-shot and one-shot them respectively, and her spawned Skeletons can distract them so she is not harmed. She is also a good counter against Graveyards, thanks to her Skeletons and quick ranged attack that leave no enemy Skeleton untouched.
The Witch has a moderate amount of hitpoints and damage potential. She can either spawn Skeletons to tank in damage that would have been directed at the Witch or continually spawn Skeletons to deal more damage to the Crown Tower if said Crown Tower is targeted at her, as the spawned Skeletons can deal more damage than the Witch herself.
If a Witch summons while under Rage, her Skeletons are also affected. Keep this in mind when going on the offensive.
Pair her up with other troops because she herself does very little damage.
The Witch is a good counter for the Sparky. If deployed correctly, she will be able to distract the Sparky multiple times with her Skeletons, allowing herself and/or other troops to deal heavy damage to it. However, don't use her if Sparky is paired up with area damage troops, such as the Wizard.
The Valkyrie is a good counter to the Witch as her axe can wipe out the spawned Skeletons and her high hitpoints are able to take up many hits from the Witch. However, if deployed carefully, the Witch is also able to counter the Valkyrie.
The Witch was added with Clash Royale's soft launch on 4/1/16.
On 11/1/16, a Balance Update decreased the Witch's spawned Skeletons level by 1. Before this update, a Level 8 Witch would be able to spawn level 14 Skeletons.
On 3/5/16, the May 2016 Update fixed the "range bug" and decreased the Witch's range to 5 (from 5.5) but her effective range is unchanged. Also, before the change Witch was able to summon level 13 Skeletons while the level cap for the Skeletons card was 12. The Goblin Barrel was able to do the same with the Goblins.
On 18/5/16, a Balance Update increased the Witch's damage by 10%. In addition, the Skeletons' hitpoints and damage were increased by 5%.
There was a bug with the Witch where she could be trapped in a corner of your territory by any building, such as the Goblin Hut or Barbarian Hut, which players utilized to use the Witch as an additional spawner, before the building trapping the Witch was destroyed and she could continue on as a normal troop.
She and other troops still seem to "bounce" around tight spaces between buildings.
In Clash of Clans, the Witch gets around by floating, whereas in Clash Royale, she walks instead. In Clash of Clans, the Witch stops and spawns Skeletons in a small circular area around her. However, in Clash Royale, she spawns Skeletons directly in front of her while walking.
The Witch is the only troop in the game that can summon other troops while she is alive. The Lava Hound and the Golem spawn Lava Pups and Golemites when they die.