Cryptborn Horror

A 0/0 that does nothing until your opponents start bleeding, and everything once they do. The body is entirely conditional: it enters carrying +1/+1 counters equal to the life your opponents have lost this turn, so cast on a clean board it arrives as a 0/0 and dies to state-based actions on the spot. That makes it a payoff card masquerading as a creature, dependent on the deck around it to do the violence first. The natural home is the aristocrats-and-aggression overlap where Rakdos lives: a few cheap drainers, a burn spell, a pinger or a Blood Artist effect resolving before this hits the stack, and suddenly the three-mana investment lands as a four-, five-, six-power trampler. The trample is not incidental; once the engine has paid out, you want the surplus damage going somewhere, and a chunky body chump-blocked into nothing would waste the counters you stacked onto it. What it really rewards is sequencing: every point of life loss you route through your opponents before this resolves is locked permanently into the body, since the counters persist after the turn ends. Get the order right and it is a finisher; cast it cold and it falls over before it can swing.