Venerated Rotpriest

Most poison payoffs care about how much combat damage you connect with; this one flips the incentive to how many spells you can point at your own board. The second ability turns every targeted spell you cast on your creatures (a pump spell, a protective flash, a bounce, an aura) into a poison counter for an opponent, which means the deck stops caring about attacking through blockers and starts caring about accumulating cheap, targeted interaction that would normally read as pure defense. That reframing is the whole design: it takes the ceiling off toxic by decoupling poison from combat, and it makes spells you were going to cast anyway do double duty. The trigger fires on any creature you control becoming a target, so it rewards decks built to hold up instant-speed responses rather than commit to a single alpha strike, and it stacks with the Toxic 1 on its own body when it does connect. The 1/2 frame is the balancing hand here: it dies to almost everything and invites the removal that would otherwise be a clean answer, except that pointing removal at it does nothing to stop the engine once the counters are already banking. It is the rare one-drop whose best-case line involves your opponent spending a card to kill it and still losing ground to the spells you were casting on your own side of the table.