Bedlam Reveler

The cost reduction is the entire engine, and it inverts the normal relationship between a deck's spell density and its threats. The printed on the card is a fiction: with a graveyard stuffed full of spent instants and sorceries, the body can come down for two or three mana, and the discard-then-draw-three on entry refills a hand emptied by a turn of cantrips and burn. That refill is the genius of the design and also its restraint. A spellslinger deck that fizzles out of cards normally has to grind toward more gas; this asks you to spend everything first, then trade an empty hand for a fresh three. The two halves of the card care about different things, which is easy to miss: only instant and sorcery cards in the graveyard shave off the cost, while prowess triggers on any noncreature spell you cast afterward. So the discount is a reward for a game already played, and the pump is a reward for the turn still ahead. Once it resolves, the 3/4 body does not grow with the game state on its own; only prowess lifts it, and only for the turn. As a creature it is fragile and slow. As a payoff for a deck that treats instants and sorceries as its real creatures, it is the rare threat that arrives cheaper and with a full hand precisely when a normal deck would be running on empty.