Contaminant Grafter

Poison in green usually means a body that pushes counters through and little else; this one closes the loop between chip damage and payoff. The combat trigger fires off any of your creatures connecting, not just this one, so a wide poison board turns every attack step into a proliferate: the single toxic counter it carries is almost incidental next to the counters it multiplies for everyone else. The Corrupted clause is the reward that makes the whole engine worth assembling. Once an opponent sits at three poison, the end step hands you a card and a free land drop, which is the rare thing in a poison shell: card advantage and mana development stapled to a plan that is otherwise a race. The design tension is that both halves want the same thing. You need creatures already dealing damage to fuel the proliferate, and you need an opponent already deep into the poison track to switch on the draw, so the card rewards a board state that is already ahead rather than one that is behind. It is a five-mana 5/5 with trample that asks you to have built the infect-adjacent battlefield first, then pays you handsomely for having done so.