Aethertide Whale

Energy was the mechanic built around a counter that didn't expire between turns, and most of the cards that fed it asked you to spend that resource on a small, immediate edge. This one inverts the relationship: it pays its full energy cost back up front, handing you six counters the moment it lands, then offers to consume four of them to bounce itself to hand. Read at face value that ability looks defensive, a way to dodge removal by paying a tax. The more interesting use is offensive recursion. Each cast banks six energy; each bounce costs four; the math leaves you a net of two energy per loop, so a recurring 6/4 flier doubles as a slow energy battery that funds the rest of your deck. The body itself is the wrinkle that makes the loop worth running: a six-power evasive threat is enough to close a game on its own, so you are never paying for the engine with a do-nothing creature. The friction is the mana. Recasting a six-mana creature every turn is a real commitment, which keeps the loop honest in a way the energy economy alone never would. It sits at the top of the energy curve as the payoff that decides whether you've built a deck that merely accumulates the resource or one that actually turns it back into pressure.