Penumbra Wurm

Killing this thing once does not finish the job: it dies into a fresh 6/6 trampler that lands in black, the opposite corner of the color pie from the green body you just answered. The front half is a plain trampling 6/6 that would barely register at seven mana alone, but the death trigger makes it a creature that demands two answers, and not just any answers. A standard sweeper makes the problem worse: wrath the board and the controller is left with a 6/6 token staring at your empty side. What actually stops it is exile, a bounce that pre-empts the death clause, or a tuck effect. The structure is recursion-by-replacement rather than recursion-from-the-graveyard, so it asks nothing of the graveyard and slips past the graveyard hate that polices reanimation; the replacement body simply appears. The color flip is the wrinkle worth dwelling on. In a green deck you spend the front half in green and collect the back half in black, which matters when an opponent has leaned on green-specific removal or color-pinpoint protection: the second beater walks under all of it. This is the enemy-color experimentation of an earlier era given creature form, a green body whose insurance policy is deliberately written in black, the seam between the two halves doing all the work the rate alone never could.