Rin and Seri, Inseparable

Whenever you cast a Dog spell, create a 1/1 green Cat creature token.
Whenever you cast a Cat spell, create a 1/1 white Dog creature token.
{R}{G}{W}, {T}: Rin and Seri, Inseparable deals damage to any target equal to the number of Dogs you control. You gain life equal to the number of Cats you control.

Awaken the Woods

Create X 1/1 green Forest Dryad land creature tokens. (They're affected by summoning sickness.)

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Moonshaker Cavalry

Flying
When Moonshaker Cavalry enters, creatures you control gain flying and get +X/+X until end of turn, where X is the number of creatures you control.

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

Mondrak, Glory Dominus

If one or more tokens would be created under your control, twice that many of those tokens are created instead.
{1}{W/P}{W/P}, Sacrifice two other artifacts and/or creatures: Put an indestructible counter on Mondrak, Glory Dominus. ({W/P} can be paid with either {W} or 2 life.)

Second Harvest

For each token you control, create a token that's a copy of that permanent.

Craterhoof Behemoth

Haste
When Craterhoof Behemoth enters, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.

Felidar Sovereign

Vigilance (Attacking doesn't cause this creature to tap.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
At the beginning of your upkeep, if you have 40 or more life, you win the game.