Duplicant

Imprint — When Duplicant enters, you may exile target nontoken creature.
As long as a card exiled with Duplicant is a creature card, Duplicant has the power, toughness, and creature types of the last creature card exiled with Duplicant. It's still a Shapeshifter.

Valakut Fireboar

Whenever Valakut Fireboar attacks, switch its power and toughness until end of turn.

Palisade Giant

All damage that would be dealt to you and other permanents you control is dealt to Palisade Giant instead.

Brash Taunter

Indestructible
Whenever Brash Taunter is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: Brash Taunter fights another target creature.

Combat Thresher

Prototype {2}{W} — 1/1 (You may cast this spell with different mana cost, color, and size. It keeps its abilities and types.)
Double strike
When Combat Thresher enters, draw a card.

Meteor Golem

When Meteor Golem enters, destroy target nonland permanent an opponent controls.

Crested Sunmare

Other Horses you control have indestructible.
At the beginning of each end step, if you gained life this turn, create a 5/5 white Horse creature token.

Workhorse

Workhorse enters with four +1/+1 counters on it.
Remove a +1/+1 counter from Workhorse: Add {C}.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Thundermare

Haste (This creature can attack and {T} as soon as it comes under your control.)
When Thundermare enters, tap all other creatures.

Mana Flare

Whenever a player taps a land for mana, that player adds one mana of any type that land produced.

Shadowfax, Lord of Horses

Horses you control have haste. (They can attack and {T} as soon as they come under your control.)
Whenever Shadowfax, Lord of Horses attacks, you may put a creature card with lesser power from your hand onto the battlefield tapped and attacking.

Goring Ceratops

Double strike
Whenever Goring Ceratops attacks, other creatures you control gain double strike until end of turn.

Big Score

As an additional cost to cast this spell, discard a card.
Draw two cards and create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Gamble

Search your library for a card, put that card into your hand, discard a card at random, then shuffle.

Bill the Pony

When Bill the Pony enters, create two Food tokens. (They're artifacts with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
Sacrifice a Food: Until end of turn, target creature you control assigns combat damage equal to its toughness rather than its power.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Havoc Eater

Flying
When Havoc Eater enters, for each opponent, goad up to one target creature that opponent controls. Put X +1/+1 counters on Havoc Eater, where X is the total power of creatures goaded this way.

Weathered Bodyguards

As long as Weathered Bodyguards is untapped, all combat damage that would be dealt to you by unblocked creatures is dealt to Weathered Bodyguards instead.
Morph {3}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Keleth, Sunmane Familiar

Whenever a commander you control attacks, put a +1/+1 counter on it.
Partner (You can have two commanders if both have partner.)

Ivory Giant

When Ivory Giant enters, tap all nonwhite creatures.
Suspend 5—{W} (Rather than cast this card from your hand, you may pay {W} and exile it with five time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)

Protector of the Crown

When Protector of the Crown enters, you become the monarch.
All damage that would be dealt to you is dealt to Protector of the Crown instead.

Aurelia, the Warleader

Flying, vigilance, haste
Whenever Aurelia, the Warleader attacks for the first time each turn, untap all creatures you control. After this phase, there is an additional combat phase.

Lightning Mare

This spell can't be countered.
Lightning Mare can't be blocked by blue creatures.
{1}{R}: Lightning Mare gets +1/+0 until end of turn.