Barbarian Ring

{T}: Add {R}. This land deals 1 damage to you.
Threshold — {R}, {T}, Sacrifice this land: It deals 2 damage to any target. Activate only if seven or more cards are in your graveyard.

Seedtime

Cast this spell only during your turn.
Take an extra turn after this one if an opponent cast a blue spell this turn.

Mountain

Crimson Hellkite

Flying
{X}, {T}: This creature deals X damage to target creature. Spend only red mana on X.

Elvish Piper

{G}, {T}: You may put a creature card from your hand onto the battlefield.

Fiery Temper

Fiery Temper deals 3 damage to any target.
Madness {R} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Dwell on the Past

Target player shuffles up to four target cards from their graveyard into their library.

Karplusan Forest

{T}: Add {C}.
{T}: Add {R} or {G}. This land deals 1 damage to you.

Crashing Centaur

{G}, Discard a card: This creature gains trample until end of turn.
Threshold — As long as seven or more cards are in your graveyard, this creature gets +2/+2 and has shroud. (It can't be the target of spells or abilities.)

Firebolt

Firebolt deals 2 damage to any target.
Flashback {4}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Forest

Centaur Garden

{T}: Add {G}. This land deals 1 damage to you.
Threshold — {G}, {T}, Sacrifice this land: Target creature gets +3/+3 until end of turn. Activate only if seven or more cards are in your graveyard.

Creeping Mold

Destroy target artifact, enchantment, or land.

Flametongue Kavu

When this creature enters, it deals 4 damage to target creature.

Aether Flash

Whenever a creature enters, this enchantment deals 2 damage to it.

Bloodfire Colossus

{R}, Sacrifice this creature: It deals 6 damage to each creature and each player.

Mossfire Valley

Centaur Rootcaster

Whenever this creature deals combat damage to a player, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Brawn

Trample
As long as this card is in your graveyard and you control a Forest, creatures you control have trample.

Genesis

At the beginning of your upkeep, if this creature is in your graveyard, you may pay {2}{G}. If you do, return target creature card from your graveyard to your hand.

Aether Rift

At the beginning of your upkeep, discard a card at random. If you discard a creature card this way, return it from your graveyard to the battlefield unless any player pays 5 life.

Birds of Paradise

Anger

Haste
As long as this card is in your graveyard and you control a Mountain, creatures you control have haste.

Wild Mongrel

Discard a card: This creature gets +1/+1 and becomes the color of your choice until end of turn.