Neoform

Sacrifice a creature, fetch one whose mana value is precisely one higher: the +1 constraint that governs this tutor is also what keeps it from being a straight reanimation cheat, because you cannot dig arbitrarily deep. The deck has to be built as a ladder where every rung is legal. The explosive line is not sacrificing free tokens (a token's mana value is zero, so it only fetches a one-drop). It comes from sacrificing a creature that carries a large mana value but arrived cheaply: something cast off an alternative cost, discounted, or put into play for a fraction of its printed cost, then converted into a creature one step larger still. It descends from the Birthing Pod line of tutor-and-cheat effects, but where that card climbed the ladder repeatedly at the recurring life cost of Phyrexian mana, this is a single sorcery-speed transaction: one creature in, one bigger creature onto the battlefield, with a counter to sweeten the trade. That one-shot nature is the tax. You spend a card and a body to convert one mana value into the next, so the fetched creature has to close the game or assemble a combo the instant it lands, because there is no second activation to fall back on. The +1/+1 counter reads like a footnote next to the tutor, but on a creature whose value keys off a power threshold, that extra counter is occasionally the line between a body that stalls and one that ends the turn.