Dirge Bat

Mutate promised removal on demand for anyone willing to commit two cards to a single stack, and this is where the mechanic collided most directly with a Doom Blade. There are two ways to spend it, and only one turns on the payoff. Cast it for its printed cost and you get a flash flier, a fine but unremarkable 3/3 with nothing more. Cast it as a mutate spell and the mutate trigger fires, destroying an opponent's creature or planeswalker while your pile of abilities grows taller. The design tension is that mutate rewards repetition: every subsequent creature you stack onto the pile mutates again, and every mutation re-triggers the destroy clause, so a late-game sequence can chain several kill spells off one board. What makes the removal a genuine ambush is where flash and mutate overlap. Because flash rides on the card itself, you can hold up the mutate cost and land the destroy trigger on an opponent's turn, punishing a swing or catching a tapped-out planeswalker deck flat-footed. That reach has a real limit: a walker that resolves on its controller's turn gets to activate a loyalty ability before you ever get the chance to mutate in response, so the ambush answers established threats better than freshly-cast ones. The whole thing is fragile: the pile heads to the graveyard the moment the base creature dies, and the mutate figure both taxes you above the hard cast and demands a non-Human creature already down to graft onto. It is the payoff end of a mechanic that otherwise traded in incremental stat-stacking: a reusable hard answer at the moment of your choosing.