Using Creatures

From Archon Arcana - The KeyForge Wiki

When the active player uses a creature, that player must exhaust the creature, and the player has the option to reap, fight, resolve the creature’s “Action:” ability, or resolve the creature’s “Omni:” ability. Any card effect that causes a creature to fight, reap, resolve its “Action:” ability, or to resolve its “Omni:” ability is causing that creature to be used.

KeyForge Master Rulebook v17.2 October 2023