Altaïr Ibn-La'Ahad

The whole card is built around a resource almost nothing else in the game touches: creature cards in exile with memory counters on them. The attack trigger does two jobs at once. First it reaches into the graveyard and exiles a single Assassin, stamping it with a memory counter and adding it to the pool. Then it counts every counter-marked creature card you own out in exile and pours a tapped, attacking copy of each onto the battlefield alongside him. So Altaïr seeds his own engine one card at a time, but the pool is cumulative across turns: every swing widens the next one, and any other effect that parks counter-marked cards in exile deepens the payout faster than his trigger alone can. The end-of-combat exile clause is what keeps this from snowballing into a permanent army: the tokens vanish each turn, so the reward is a recurring alpha strike rather than a board you build once and leave standing. First strike on a 3/3 body reads as a minor combat perk, but on a creature meant to lead the same widening charge every turn, it makes each attack a favorable exchange rather than a trade. This is less a finisher than an accumulation engine, and its ceiling is set entirely by how many counter-stamped creature cards you can bank in exile before combat.