Boon of Boseiju

Pump spells that scale with your board are old, but the scaling axis here is what makes it strange: the bonus keys off the greatest mana value among your permanents, not the number of creatures you have. One expensive permanent does all the lifting. That decouples the payoff from going wide: a lone ramp target, a big planeswalker, even a costly artifact or enchantment turns any creature into a serious threat at instant speed, and it does not care whether the rest of your board is empty. The untap rider elevates it past a plain combat trick. Cast it during your combat step and the pumped creature can attack again if another effect grants a second attack, or (cast on defense) untap a creature that was tapped so it can block the swing back. That flexibility, priced at two mana, is gated behind the deckbuilding cost of actually having a high-mana-value permanent to point at; the ceiling only exists if you built toward it. The design answers a recurring green problem, the board that is bigger but stalled, by rewarding vertical investment rather than horizontal spread: it pays you for the expensive thing you already committed to, and lets the opponent walk into a combat math that the empty-looking board never advertised.