Oathbreaker: Nissa, Voice of Zendikar

Signature Spell: Scatter the Seeds

The best board state is to have Nissa, Voice of Zendikar on the board, a few creatures (plant, saproling, etc.), and Paradox Engine on the battlefield. You can convoke and cast Scatter the Seeds, which will create three new saprolings. If you have enough creatures Paradox Engine will untap all the ones that were used for convoke, then you can cast Scatter the Seeds ad nauseum.

The deck also has sorceries to help draw, artifacts and enchantments to pump up your army, and other utilities like Cryptolith Rite and Fungal Plots.