Prosper, Tome-Bound

Rakdos players had been faking this card for years, stitching together impulse-draw effects and sacrifice loops to grind an opponent out; here that whole improvised engine arrives assembled on one four-mana body. The Mystic Arcanum trigger exiles your top card at the beginning of your end step and keeps it castable through your next turn, which matters because you untap first and get a fresh mana pool to spend rather than scraping for leftovers on the end step you exiled it. Pact Boon is the multiplier: a Treasure every time you play a card from exile. Because the impulse exile is itself a source of cards-from-exile, the engine partly refunds its own cost in ritual mana. Feed it any other exile-cast effect (adventures, foretell, cascade, suspend, anything you play from a face-up exile zone) and the Treasures compound faster than raw card advantage would suggest. The 1/4 with deathtouch is not an attacker; it is a defensive shell built to weather a few turns while the value structure does the killing, a body that punishes anything foolish enough to trade with it. Two clocks on the same tick: card advantage and ritual mana, generated together, aimed at burying the opponent rather than racing them.