Core Prowler

Most infect creatures threaten the player; this one threatens the clock. The death-triggered proliferate is the design fulcrum: a 2/2 with infect that dies in combat or to removal does not just trade, it advances every poison counter you have already landed, turning a chump block into another point of damage on the long game. That symmetry between infect and proliferate is the elegant part. The same mechanic that puts poison counters on opponents also lets the creature top them off as it leaves, which means trading it away is rarely a clean exit for the defender. Note that proliferate is open-ended, so the trigger reaches charge counters, loyalty, and anything else accumulating on the board, not only the poison it pairs with most naturally. As a colorless body, it slips into any deck willing to commit to a poison plan or a counter-matters engine, which is the quiet reason it has outlived most of its infect contemporaries: the death trigger is useful even when the infect line is not the one you are pursuing. Plenty of infect creatures wanted to connect and never come back; this one is built to make its death the payoff.