Felix Five-Boots

The doubler here is a doubler of a very specific shape: it does not copy your spells or your enters-the-battlefield triggers, only the triggers a permanent you control fires when one of your attackers connects. That narrows the payoff to a category most decks barely track, then rewards you for stacking it deliberately. Every "whenever a creature you control deals combat damage" line resolves twice per hit: card draw off connecting attackers, life drain, treasure and clue generation, even the punisher effects that ping the defending player. The 5/4 body is not incidental to that plan; it is the delivery system. Menace makes this Ooze hard to chump, so it keeps arriving at the red zone to fuel whatever on-hit engine you have assembled, while ward taxes the removal that would otherwise cut the doubler short before it swings. The design discipline is that the ability offers nothing to the ramp-and-goodstuff piles this color trio usually attracts. It demands a critical mass of combat-damage triggers before the multiplier earns its slot, and it only ever doubles what you had to push through the combat step: combat damage that never reaches a player pays nothing, and damage that never lands on a player does nothing at all. Note that the body carries no innate connect trigger of its own; it is the enabler, and the payoffs are yours to supply. A build-around masquerading as a value engine, and the difference is the whole point.