Activated Sleeper

Clone effects usually reach across the battlefield: pick something in play, become it, ride the copy. This one reaches into the graveyard instead, and only into a narrow slice of it: a creature that died this turn, killed by combat or removal or a sacrifice you engineered on purpose. The window is what defines it. You are not answering the board as it stands; you are answering what just left it, at instant speed, after the removal spell or the block that put the creature there. Flash is doing the heavy lifting: let a removal spell or a block resolve, let the creature hit the yard, and cast this in the aftermath so the corpse becomes your body before the turn passes. That timing rewrites how a trade resolves, since the creature your opponent just spent a card to kill can be reborn under your control the same turn. The Phyrexian type it grafts on is more than a flavor tax; it plugs the copy into compleation-matters and Phyrexian-tribal payoffs that the original creature would never have qualified for. As a 0/0 with no fresh corpse to seize, it simply dies, so the whole design leans on there being graveyard fodder freshly put there from the battlefield. It is the reanimation instinct compressed into a single reactive window: not the slow, sorcery-speed dig of a big reanimator spell, but a knife-edge steal timed to the moment a creature hits the yard.