Retaliating specifically refers only to the inherent ability to deal Thorns damage to enemies when they Hit you.
Some effects may cause you to deal Thorns damage in other ways, but those are not Retaliation, and effects which specifically care about when you Retaliate will ignore them.
Supports MeleeAttack Skills. Supported Skills trigger Quill Burst, which deals your Thorns Damage in an Area around the target struck. Quill Burst can only be triggered on Hit after you've
Retaliated with Thorns Damage.