Albino Troll

A 3/3 for two mana would have been aggressively undercosted in this era, and echo is the leash that paid for the discount: the troll lands at face value, but at your following upkeep you either feed it the echo cost or sacrifice it. You only truly own the creature once you have paid for it twice, and that deferred invoice is what kept the rate from breaking green's curve. The regeneration ability layers a second kind of resilience on top, turning a beater that already overcommits on size into one that walks through most sweepers and grinds combat indefinitely once the echo is settled. The wrinkle worth flagging is how echo travels with control: bounce it, blink it, or steal it, and the new controller inherits the upkeep obligation from scratch, so a creature that reads as raw stats actually carries a fragility the stat line does not advertise. It is a clean record of green's bargain with front-loaded creatures from this period: designers got to price big bodies below their stat line, and the second payment at upkeep is what kept that deal honest rather than a 3/3 you simply paid two mana for once.