Use Sachi, Daughter of Seshiro and her army of mostly female shamans to make lots of mana to cast enormous creatures, and lots, and lots, and lots of smaller ones.
Mana, Draw, and Acceleration - Frontier Guide lets you search for land to thin out your deck and add to your mana, and Perilous Forays is a late-game way to really boost mana and thin out the deck. Leaf-Crowned Elder drops Shamans for free, Oracle of Mul Daya can drop free land, and Fa'adiyah Seer can be a free card draw. Elvish Visionary and Masked Admirers are cantrips that can be tapped for mana with Sachi, and Collective Unconscious refills your hand once you've dropped down a few creature tokens. Fauna Shaman helps you find creatures you need. And finally, Citanul Hierophants, even though he's not a shaman, works wonders in this deck as he turns all your creature tokens into potential Llanowar Elves.
Token Generators - Orochi Hatchery works great once you have a huge mana base. Orochi Eggwatcher, Wren's Run Packmaster, Ant Queen, Jade Mage, and Centaur Glade make tokens for mana. Wolf-Skull Shaman makes freebies, while Kazandu Tuskcaller makes tokens by tapping once leveled up. Living Hive can make insects when attacking. Sacrifice creatures to Spawning Pit if they're on the way to the graveyard anyway, and make more creatures with it, or pump up creatures and sacrifice them to Ooze Garden.
Graveyard - Loaming Shaman and Elixir of Immortality are ways of recycling your graveyard, Moldegraf Monstrosity can get you 2 random creatures back when it dies, and Night Soil can get rid of your opponents' graveyards.
Life and Death - Essence Warden gains you life whenever you (frequently) drop creatures, while Lumberknot grows quickly in size whenever a creature dies, and Guttergrime gives you oozes whenever a nontoken creature dies. But the most fun is Thornbite Staff. Take this combo for example: Any shaman with Sachi in play equipped with Thornbite Staff + Ant Queen + Perilous Forays = search your library for a land and put it into play tapped for only 1 colorless mana.
Defense - There's plenty of ways to gain life with this deck. Essence Warden for persistant life gain, while there's also Stream of Life and Taste of Paradise for one-off life gain. And Claws of Gix for sacing weenies for life in a pinch. But Blunt the Assault is the best of all - a fog that gives you life equal to the number of creatures in play. Wrap in Vigor can save you from a pesky board wipe. Hurricane is for dealing with fliers, and for dealing hefty damage to your opponents (and yourself) in the process. Nullmage Shepherd, Terastodon, Viridian Shaman, Acidic Slime, and Gleeful Sabotage for pesky artifacts and enchantments. If you have Wren out, opponents will think twice about attacking you, what with all your deathtouch wolves and such.
Offense - Wildheart Invoker and Gigantomancer turn your little guys into big guys, Winter Blast can tap them out, and Overrun for a finisher. A flipped Orochi Eggwatcher can also be a game-winner, sacing just enough blocked weenies to pump them up enough to kill your opponents.