Shriekwood Devourer

Green ramp payoffs have usually split along a clean line: dorks and rituals that front-load mana into one explosive turn, or land-untappers in the Kiora's Follower and Wilderness Reclamation vein that refill your manabase before or after combat. Hooking the untap to the attack step reroutes the whole tempo of the spell. Declare an attack and you get up to X lands back, where X is the biggest attacker's power; on any board swinging with something sizable, that is a wall of mana refunded at the exact moment you would otherwise be tapped out to fight. What makes the effect coil back on itself is that the payoff scales with the same stat that makes green creatures good in combat: raw power. This is not a fragile enabler waiting to be answered before it does anything. A 7/5 with trample feeds its own trigger, untapping up to seven lands off its own attack if it survives to the declare step. That mana buys a second main phase's worth of plays without passing the turn, so any pump spell, flash threat, or reactive answer becomes something you can hold up while still committing to the beatdown. The limiter sits on the back of the body: at five toughness it dies to most sweepers and a fair amount of removal before the trigger ever pays out, so it wants a board that already threatens lethal rather than one it is trying to build from nothing.