Melira, Sylvok Outcast

A 2/2 with no relevant combat presence, built entirely as an answer to two of the era's nastiest mechanics at once. The poison-immunity and infect-stripping clauses are the headline, the antidote any green deck could deploy against a creature-based mill-your-life-to-zero plan. But the second line is the one that built archetypes: creatures you control can't have minus-one-minus-one counters put on them. That single immunity quietly broke a whole category of "until end of turn" balance lines and, more importantly, undid the death step of every persist creature. A persist creature dies, returns with a minus-one-minus-one counter, and is one death away from gone for good. With this on the battlefield, that counter never lands, so the creature comes back at full size and stays a persist creature forever. Pair that with a free sacrifice outlet and a payoff and you have an infinite loop assembled from three otherwise-fair pieces. That interaction, not the hatebear text, is why the card has a reputation that outlasts the poison threat it was printed to police. It is a hate card whose most consequential ability is the one that reads like a footnote: a defensive immunity that doubles as the keystone of a combo, depending entirely on what else is on your side of the table.