Yawgmoth's Day Planner

Three lines that only cooperate if you read them together, wrapped in the deadpan of a corporate day planner bearing Yawgmoth's name. The mana ability pays two life for two black, and the graveyard-casting permission carries a rider that looks like flavor filler but is the entire mechanism: only mana produced by abilities that made you lose life can pay for those recasts. That marries the two halves. The artifact is the advertised source of its own "life-loss mana," so it fuels its own recursion, and it will accept life-loss mana from other sources too. The exile-replacement clause reads like it should slam the loop shut, and largely it does: an instant or sorcery is put into the graveyard as the last step of its own resolution, so the replacement effect catches it there and exiles it, resolved or countered alike. The recursion is therefore single-shot per card rather than a perpetual engine; you get one recast, then the spell is gone. That is the puzzle the card sets. The design threads loss-of-life mana through a graveyard filter into an exile hatch, and it only pays off for a player who sequences all three restrictions in the right order. The name and the office-supply framing are the wink; underneath sits a genuinely tight interaction of a mana constraint, a casting permission, and a replacement effect that refuse to work unless you assemble them precisely.