Primordial Ooze

A red one-drop that grows itself for free is a design contradiction, and this card owns the contradiction by writing the bill into the upkeep step. The +1/+1 counter arrives automatically, then the cost to avoid the penalty is exactly the number of counters on it: one mana the turn it has one, two the next, three the turn after, a linear tax that tracks the body's size to the dot. The number stays small for a while, but it never stops climbing, and the moment you skip the payment the creature taps and deals damage equal to that counter count straight to your face. The mandatory-attack clause completes the trap, removing the option to sandbag the growing body as a blocker; once you have it, you are committed to racing with it. Read together, the two clauses model a creature that is genuinely feral, an organism that grows whether you feed it or not and bites the hand that cannot keep paying. Most drawback creatures of the era priced their downside as a static cost (Juzám Djinn's flat upkeep ping, for one); this one prices it as rent that escalates with the asset, a sharper and more honest way to model a creature you cannot really control. The template never caught on, but the underlying idea (a self-growing beater you lease by the turn, on terms that only ever get worse) is one of the more interesting things red was trying to say in its first few years.