Destroy any number of creatures opponents controlDestroy any number of creatures opponents control whenever you put a counter on a permanent or playerInfinite -1/-1 counters on creatures opponents controlLock
How it works
Attempt to deal noncombat damage to a creature an opponent controls, instead putting that many -1/-1 counters on it due to Soul-Scar Mage.
All Will Be One triggers, putting that many -1/-1 counters on a creature an opponent controls.