Avoid this Deck like the Plague (Casual)

Dole out as many Poison Counters as possible, as fast as possible. This deck tends to win before turn 4, and can usually scrape out a second kill by turns 9 or 10 in a multiplayer game. Play creatures early, then attack as soon as possible and pump the bejeezus out of anything that gets through.

Optimal scenario for this deck:
First hand with at least one Glistener Elf, A green mana source, and enough pump spells for +9/+9
T1: Yavimaya Coast/Pendelhaven/Forest, drop a Glistener Elf.
T2: Hinterland Harbor/Yavimaya Coast/Island for any blue spells on hand, swing with Glistener Elf and unleash every pump spell you've got.

If you don't happen to draw into a Glistener Elf, any of the other creatures work the same way for a win as early as turn three.

Sideboard is for playing against burn. If possible, still avoid it at all costs. Well-built burn decks are the only archetype I've encountered that are able to put up a fight against this deck.

To bring down the cost of this deck without affecting the play too much, just swap out the nonbasic lands for more Forests/Islands to taste.