Rockfall Vale

This land enters tapped unless you control two or more other lands.
{T}: Add {R} or {G}.

Horizon Stone

If you would lose unspent mana, that mana becomes colorless instead.

Flowstone Giant

{R}: This creature gets +2/-2 until end of turn.

Stone Calendar

Brion Stoutarm

Lifelink
{R}, {T}, Sacrifice another creature: Brion Stoutarm deals damage equal to the sacrificed creature's power to target player or planeswalker.

Redrock Sentinel

Defender
{2}, {T}, Sacrifice a land: Draw a card and create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Crimson Roc

Flying
Whenever this creature blocks a creature without flying, this creature gets +1/+0 and gains first strike until end of turn.

Stone of Erech

If a creature an opponent controls would die, exile it instead.
{2}, {T}, Sacrifice Stone of Erech: Exile target player's graveyard. Draw a card.

Rock Hydra

This creature enters with X +1/+1 counters on it.
For each 1 damage that would be dealt to this creature, if it has a +1/+1 counter on it, remove a +1/+1 counter from it and prevent that 1 damage.
{R}: Prevent the next 1 damage that would be dealt to this creature this turn.
{R}{R}{R}: Put a +1/+1 counter on this creature. Activate only during your upkeep.

Rock Badger

Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)

Rock Jockey

You can't cast Rock Jockey if you've played a land this turn.
You can't play lands if this creature was cast this turn.

Stonecoil Serpent

Reach, trample, protection from multicolored
This creature enters with X +1/+1 counters on it.

Corrupted Grafstone

This artifact enters tapped.
{T}: Choose a color of a card in your graveyard. Add one mana of that color.

Boiling Rock Prison

This land enters tapped.
{T}: Add {B} or {R}.
{4}, {T}, Sacrifice this land: Draw a card.

Rockslide Elemental

First strike
Whenever another creature dies, you may put a +1/+1 counter on this creature.

Sandstone Oracle

Flying
When this creature enters, choose an opponent. If that player has more cards in hand than you, draw cards equal to the difference.

Stone Idol Trap

This spell costs {1} less to cast for each attacking creature.
Create a 6/12 colorless Construct artifact creature token with trample. Exile it at the beginning of your next end step.

Flowstone Kavu

Menace (This creature can't be blocked except by two or more creatures.)
{R}: This creature gets +1/-1 until end of turn.

Madblind Mountain

({T}: Add {R}.)
This land enters tapped.
{R}, {T}: Shuffle your library. Activate only if you control two or more red permanents.

Boulder Rush

Target creature gets +2/+0 until end of turn. (Then exile this card. You may cast the creature later from exile.)

Rimrock Knight

Rimrock Knight // Boulder Rush

Roc Hatchling

This creature enters with four shell counters on it.
At the beginning of your upkeep, remove a shell counter from this creature.
As long as this creature has no shell counters on it, it gets +3/+2 and has flying.

Brainstone

{2}, {T}, Sacrifice this artifact: Draw three cards, then put two cards from your hand on top of your library in any order.

Flowstone Hellion

Haste
{0}: This creature gets +1/-1 until end of turn.

Roc Egg

Defender (This creature can't attack.)
When this creature dies, create a 3/3 white Bird creature token with flying.

Chained to the Rocks

Enchant Mountain you control
When this Aura enters, exile target creature an opponent controls until this Aura leaves the battlefield. (That creature returns under its owner's control.)

Ancient Stone Idol

Flash
This spell costs {1} less to cast for each attacking creature.
Trample
When this creature dies, create a 6/12 colorless Construct artifact creature token with trample.

Bloodrock Cyclops

This creature attacks each combat if able.

Akki Rockspeaker

Goblin Rock Sled

Trample
This creature doesn't untap during your untap step if it attacked during your last turn.
This creature can't attack unless defending player controls a Mountain.

Rockshard Elemental

Double strike (This creature deals both first-strike and regular combat damage.)
Morph {4}{R}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)