Chaos Strike is available to starting demon hunters before choosing a specialization.
The ability is replaced by [Soul Cleave] for Vengeance demon hunters.
Trivia
Chaos Strike is a basic demon hunter spell in Hearthstone. The flavor text reads: "What do we want?" "CHAOS!" "When do we want it?" "WHEN LEAST EXPECTED!"
Patch changes
Patch 7.1.5 (2017-01-10): Damage have been slightly increased.