Elvish Champion

Other Elf creatures get +1/+1 and have forestwalk. (They can't be blocked as long as defending player controls a Forest.)

Thopter Pie Network

At the beginning of your upkeep, if you're eating, create a 1/1 colorless Thopter artifact creature token with flying. Use food to represent the token.
Whenever a creature token you control dies, if it's represented by food, eat it.

Cavern of Souls

As Cavern of Souls enters, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

Mox Lotus

{T}: Add {∞}.
{100}: Add one mana of any color.

Force of Vigor

If it's not your turn, you may exile a green card from your hand rather than pay this spell's mana cost.
Destroy up to two target artifacts and/or enchantments.

Symbol Status

Create a 1/1 colorless Expansion-Symbol creature token for each different expansion symbol among permanents you control.

Princess Twilight Sparkle

Flying
Other Alicorns, Horses, Pegasi, Ponies, and Unicorns you control get +1/+1.
{W}{U}{B}{R}{G}: If you control Applejack, Fluttershy, Pinkie Pie, Rainbow Dash, and Rarity, everypony wins the game.

Grimlock, Ferocious King

Trample
{2}, Convert a Transformers toy you own to its other mode: Grimlock, Ferocious King becomes Grimlock, Dinobot Leader.

Grimlock, Dinobot Leader

Dinosaurs, Vehicles, and other Transformers® creatures you control get +2/+0.
{2}, Convert a Transformers toy you own to its other mode: Grimlock, Dinobot Leader becomes Grimlock, Ferocious King.

Grimlock, Dinobot Leader // Grimlock, Ferocious King

Some Disassembly Required

{B}, Sacrifice a creature: Distribute the sacrificed creature's keyword abilities among any number of other target creatures until end of turn. If it's December, you gain 1 life for each of those keywords.

Collected Company

Look at the top six cards of your library. Put up to two creature cards with mana value 3 or less from among them onto the battlefield. Put the rest on the bottom of your library in any order.

Forest

Endurance

Flash
Reach
When Endurance enters, up to one target player puts all the cards from their graveyard on the bottom of their library in a random order.
Evoke—Exile a green card from your hand.

Yavimaya, Cradle of Growth

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

City of Ass

City of Ass enters tapped.
{T}: Add one and one-half mana of any one color.

Rarity

Rare and mythic rare spells you cast cost {1} less to cast.
{1}, {T}, Reveal a My Little Pony® toy you own: Until end of turn, another target creature gains protection from each color in that toy's coat, mane, and outfit.

Evil Presents

Put a creature card from your hand into play under target opponent's control. That creature attacks each turn if able . . . and always attacks its controller.

Yule Ooze

At the beginning of your upkeep, destroy another nonland permanent chosen at random, then put a number of +1/+1 counters on Yule Ooze equal to that permanent's converted mana cost.
{R}{G}, Eat some food: Regenerate Yule Ooze.

Princess Luna

Flying
When this creature transforms into Princess Luna, choose up to six cards you own from outside the game with a moon in their art, then exile those cards. As long as those cards remain exiled, you may cast them, and your friends may cast them with your permission. (Gifts are appreciated.)

Nightmare Moon

Flying
As long as it's nighttime, Nightmare Moon gets +2/+2 and has menace.
{6}: Transform Nightmare Moon. Anypony may activate this ability or help pay the cost. When they do, they become your friend.

Nightmare Moon // Princess Luna

Fruitcake Elemental

Fruitcake Elemental is indestructible.
At the end of your turn, Fruitcake Elemental deals 7 damage to you.
{3}: Target player gains control of Fruitcake Elemental.