The "Selesnya United" deck generates wave upon wave of creatures to drown your opponent under an ocean of Saprolings and their mighty friends! Token-making cards like Fists of Ironwood Buy, Selesnya Evangel Buy, and Scatter the Seeds Buy can create a frenzy of Saprolings in no time. The convoke ability then lets you tap these creepy fungus monsters to help pay for gigantic creatures like Siege Wurm Buy or crushing spells like Overwhelm Buy.
Early in the game, create creatures quickly and frequently, using every Saproling-generating effect you can. Feel free to play Fists of Ironwood Buy on an opponent's creature just to get the Saprolings! Early on, avoid attacking or blocking with your creatures if they won't survive combat—it's much more important to build up your swarm. Any life you lose to early attacks you can easily regain later with Conclave Phalanx Buy.
Once you've assembled your token horde, you'll have three main ways to win. The first way is to use your tokens to put huge attackers into play. Thanks to the convoke mechanic, you can play Siege Wurm Buy, a 5/5 trampler, for free . . . if you also tap seven creatures. Root-Kin Ally Buy is another powerful creature with convoke. Tapping your creatures can both reduce its cost and make it enormous! Plus the more creatures you control, the bigger Scion of the Wild Buy gets. A 12/12 Scion with trample from Fists of Ironwood Buy can wreak late-game havoc.
The second way to win is with Sandsower Buy. It dominates the board once you have enough creatures, and it locks down your opponent's creatures while the rest of your army attacks. The third way is to use Selesnya Guildmage Buy, Tolsimir Wolfblood Buy, or the well-named Overwhelm Buy to give power and toughness boosts to all your creatures at once. You'll win the game in one massive, unstoppable attack.
After you've played the deck a few times, you might want to swap in more spells that go well with a lot of 1/1 Saprolings. The enchantment Glare of Subdual Buy works like Sandsower Buy, but tapping an enemy creature requires you to tap only one of your creatures, not three. From the Ninth Edition set, Glorious Anthem Buy gives all your creatures a +1/+1 bonus, and Coat of Arms Buy boosts creatures' power and toughness for each other creature of the same type in play.