Citanul Centaurs

Six power for four mana with shroud reads like theft: untargetable means removal slides off, and a 6/3 ends games quickly. The catch is echo, and the structure is the whole design. You pay to cast it, watch it sit out its first turn (echo creatures arrive summoning-sick, and the upkeep payment falls due before you can attack), then settle another during your following upkeep or send it to the graveyard. That second payment is a one-time toll, not a recurring tax that climbs each turn; once it's paid, the creature is yours free and clear. But the toll is the point: shroud on a 6/3 would be wildly undercosted at four mana paid once, so echo effectively doubles the real price and splits it across two turns, buying the opponent a window to assemble blockers or land a sweeper that ignores targeting. The shroud cuts the other way, too: you can't pump it, can't regenerate it, can't shield it from combat math, and a 6/3 trades down or dies to any blocker with three or more power standing in front of it. Echo was the era's experiment in front-loaded discounts settled later, and this is one of its bluntest expressions. The casting cost flashes a bargain; keeping the creature alive collects the rest, and the brittle 6/3 frame ensures the bargain rarely closes the game before the second bill comes due.