My opponent attacks with two 4/4 creatures. I block each of them with one 2/2 creature, but have Nim Deathmantle on the field, currently not equipped to anything. When my two 2/2 creatures are put into the graveyard after the damage step, can I pay 4 mana to save one of them, equipping the Nim Deathmantle to it, and then pay another 4 to save the other, unequip from the first 2/2 creature, and now have it equipped to the other?
It's a triggered ability, so it'll trigger every time a creature dies. If multiple creatures die simultaneously, you choose how to stack the triggers, then get to resolve them one by one.