Provoking

Certain actions have the provoking keyword. When a creature in a square that you threaten attempts to perform such an action, you can perform an opportunity attack against them as an immediate interrupt.

◌ Opportunity Attack (at-will immediate interrupt ✦ basic attack )
Trigger:	An enemy within a space that you threaten performs an action with the provoking keyword.
Effect:	You make a basic melee attack against the provoking creature.