22 Jun 2015
If you lose control of Willbreaker before its ability resolves, you won’t gain control of the creature at all.
22 Jun 2015
If Willbreaker leaves the battlefield, you no longer control it, and its control-change effect ends.
22 Jun 2015
If another player gains control of Willbreaker, its control-change effect ends. Regaining control of Willbreaker won’t cause you to regain control of the creature.