Whenever a creature with toughness 4 or greater is put into your graveyard from the battlefield, you may
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) it.
At the beginning of the end step, if three or more cards have been exiled with this artifact,
sacrificeTo sacrifice a permanent, its controller moves it from the battlefield directly to its owner’s graveyard. A player can’t sacrifice something that isn’t a permanent, or something that’s a permanent they don’t control. Sacrificing a permanent doesn’t destroy it, so regeneration or other effects that replace destruction can’t affect this action. (CR 701.21) it. If you do, return those cards to the battlefield under their owner's control.