Marsh Viper

Poison arrived as a parallel win condition, and this is among the earliest creatures built to feed it: ten counters and a player loses outright, regardless of life total. The body is almost beside the point. A 1/2 for is no threat in the damage race, but it does not have to be, because every point of damage it deals chips away at a clock that runs alongside the normal one. Two poison counters per hit means five connections end a game, and the counters are dangerous precisely because life gain does nothing to remove them once applied. The trigger keys on damage dealt to a player, not combat damage specifically, which is the quietly flexible part of the design: pair it with a way to ping a player directly and the poison flows without ever touching a blocker. Left to its own devices, though, a 1/2 has to actually connect, and that fragility is the whole story. It reads as a proof of concept rather than a finished engine: poison would not get keyword support (infect, toxic) for years, and early implementations like this one asked you to grind out connections with a vulnerable creature rather than stack counters efficiently. What makes it worth remembering is the structural idea it carries. It separates lethality from life, the seed of every poison strategy that followed, and it does so with a creature so small that the threat is entirely about the counter it leaves behind, not the point of damage it deals.