Alters the entity for which the COMBAT_TEXT_UPDATE event fires.
- string - UnitId of the entity you want receive notifications for.
- The event is tied to the entity rather than the unit -- thus, if you call CombatTextSetActiveUnit("target") and then target something else, you'll get notifications for the unit you were targeting when calling the function, rather than your new target.
- Only one unit can be "active" at a time.
- The COMBAT_TEXT_UPDATE event is used in to provide part of Blizzard's Floating Combat Text functionality; it fires to notify of aura gains/losses and incoming damage and heals.