Orb Users of Night and Day

Orb Users of Night and Day gets two orb counters.
{t}: Remove an orb counter. All creatures you don't control get -5/-5 counters until your next upkeep. They are tapped and cannot be untapped on opponet player's turn. You gain life for each creature tapped.
{t}: Remove an orb counter. Destroy all creatures on the battlefield. If they have 4 or less life counters, they are exiled. All players lose 3 life.