This lethal combination hinges on the precise math of life loss and life gain when casting Shard of the Nightbringer, whose triggered ability drains an opponent for half their life while replenishing your own. Sitting quietly on the battlefield, Enduring Tenacity is the linchpin that turns that massive life gain right back around into an equivalent burst of life loss directed at your foe. Because Enduring Tenacity's passive trigger reacts instantly to the life you gain from the Shard, the resulting double-strike of life loss instantly strips away even the highest life totals, spelling sudden doom for your target.