The easiest way to make a multiplayer infect deck is to use Hydra Omnivore with a card that gives him infect like Phyresis or tainted strike etc to wipe out everyone at once. Use any of the various umbras to protect him and make him bigger and slip through space to make him unblockable. Game over. :-) Also there are various ways and cards to cheat him quickly.
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And easier way to win turn two is to have Glistener Elf 2 forests and 1 Invigorate and a phytoburst. Play GE and one forest on turn one. Play second forest and phytoburst on Glistener elf and 1 invigorate for free on turn 2. Swing for 10 infect.