Oona, Queen of the Fae

Exile, in this design, is not the kill condition: it is the raw material. Name a color, exile X cards off an opponent's library, and every hit in that color becomes a 1/1 flier, so the cards you grind away come back across the board as a swarm that ends the game. X scales the engine from a slow drip into a lethal turn the moment the mana is there, all at instant speed while the opponent's turn passes by. The naming clause is what keeps it from being a guaranteed token factory: you have to read the opponent's deck, profiting on roughly half the exiles against a two-color list and converting most of the spells against a focused mono-color one, while their lands and off-color cards slip through as misses. The activation leans on a single hybrid pip beyond the X, payable with blue or black, which is why the loop fires off whatever land base you bring, mono-blue and mono-black builds included; that color flexibility was the structural signature of the era this design came from, when a whole set was built around a single two-color identity expressed through hybrid mana. The 5/5 flier at the head of it all is incidental to the win but real on its own, a clock that closes games even when the activated ability never reaches its lethal X.