Counterflux

This spell can't be countered.
Counter target spell you don't control.
Overload {1}{U}{U}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Goblin King

Other Goblins get +1/+1 and have mountainwalk.

Kobolds of Kher Keep

Sorrow's Path

{T}: Choose two target blocking creatures controlled by the same opponent. If each of those creatures could block all creatures that the other is blocking, remove both of them from combat. Each one then blocks all creatures the other was blocking.
Whenever Sorrow's Path becomes tapped, it deals 2 damage to you and each creature you control.

Counterlash

Counter target spell. You may cast a spell that shares a card type with it from your hand without paying its mana cost.

Counterbore

Counter target spell. Search its controller's graveyard, hand, and library for all cards with the same name as that spell and exile them. Then that player shuffles.

Snow-Covered Plains

Mold Demon

When Mold Demon enters, sacrifice it unless you sacrifice two Swamps.

Rat Colony

Rat Colony gets +1/+0 for each other Rat you control.
A deck can have any number of cards named Rat Colony.

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Counterspell

Aven Trooper

Flying
{2}{W}, Discard a card: Aven Trooper gets +1/+2 until end of turn.

Akuta, Born of Ash

Haste
At the beginning of your upkeep, if you have more cards in hand than each opponent, you may sacrifice a Swamp. If you do, return Akuta, Born of Ash from your graveyard to the battlefield.