Manaplasm

Pump keyed to mana value, not spell count, is the design decision that makes this Ooze read your turn rather than your hand. Boosts accumulate across every spell you cast, so what matters is total mana value spent: cast something with mana value five and the 1/1 swings as a 6/6, or chain enough cheap spells to reach the same weight. That distinction is the whole strategic axis, because it rules out the obvious-looking shells. Spell-count payoffs love cheap chains, but this body wants weight on the stack, and the same tapped-out turn that fuels the buff is the turn you have the least mana left to protect the body or push it through a blocker. The boost expires at end of turn, so every threat it presents is a one-turn rental that has to connect or evaporate; nothing carries over, and a chump on Tuesday is a finisher on Wednesday depending purely on what you spent. That keys it to decks built to dump a single fat spell onto the stack before combat: ramp into a haymaker, a free big spell, anything that front-loads mana value in one window rather than spreading casts thin. Held in a slower shell that wants to leave mana up, the creature contributes nothing on quiet turns, which is the honest tension at the center of the card. It wants you to assemble the kind of explosive, all-in turn that would already be winning the game, then wants that same turn to also swing a creature for lethal.