Mountain

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Mondrak, Glory Dominus

If one or more tokens would be created under your control, twice that many of those tokens are created instead.
{1}{W/P}{W/P}, Sacrifice two other artifacts and/or creatures: Put an indestructible counter on Mondrak. ({W/P} can be paid with either {W} or 2 life.)

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Enduring Courage

Whenever another creature you control enters, it gets +2/+0 and gains haste until end of turn.
When Enduring Courage dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Agate Instigator

Offspring {1}{R} (You may pay an additional {1}{R} as you cast this spell. If you do, when this creature enters, create a 1/1 token copy of it.)
Whenever another creature you control enters, this creature deals 1 damage to each opponent.

Warleader's Call

Creatures you control get +1/+1.
Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Rugged Prairie

{T}: Add {C}.
{R/W}, {T}: Add {R}{R}, {R}{W}, or {W}{W}.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice this artifact: Draw a card.

Temple of Civilization

(Transforms from Ojer Taq, Deepest Foundation.)
{T}: Add {W}.
{2}{W}, {T}: Transform this land. Activate only if you attacked with three or more creatures this turn and only as a sorcery.

Ojer Taq, Deepest Foundation

Vigilance
If one or more creature tokens would be created under your control, three times that many of those tokens are created instead.
When Ojer Taq dies, return it to the battlefield tapped and transformed under its owner's control.

Ojer Taq, Deepest Foundation // Temple of Civilization

Thrumming Stone

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your library.)

Sundown Pass

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

Plains

Ogre Battledriver

Whenever another creature you control enters, that creature gets +2/+0 and gains haste until end of turn. (It can attack and {T} this turn.)

Arabella, Abandoned Doll

Whenever Arabella attacks, it deals X damage to each opponent and you gain X life, where X is the number of creatures you control with power 2 or less.

Soul Warden

Whenever another creature enters, you gain 1 life.

Welcoming Vampire

Flying
Whenever one or more other creatures you control with power 2 or less enter, draw a card. This ability triggers only once each turn.

Hare Apparent

When this creature enters, create a number of 1/1 white Rabbit creature tokens equal to the number of other creatures you control named Hare Apparent.
A deck can have any number of cards named Hare Apparent.

Delney, Streetwise Lookout

Creatures you control with power 2 or less can't be blocked by creatures with power 3 or greater.
If an ability of a creature you control with power 2 or less triggers, that ability triggers an additional time.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is this creature's power.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Tocasia's Welcome

Whenever one or more creatures you control with mana value 3 or less enter, draw a card. This ability triggers only once each turn.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Command Tower

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Spectator Seating

This land enters tapped unless you have two or more opponents.
{T}: Add {R} or {W}.

Rising of the Day

Creatures you control have haste.
Legendary creatures you control get +1/+0.

Boros Signet

Talisman of Conviction

{T}: Add {C}.
{T}: Add {R} or {W}. This artifact deals 1 damage to you.

Battlefield Forge

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

Lupinflower Village

{T}: Add {C}.
{T}: Add {W}. Spend this mana only to cast a creature spell.
{1}{W}, {T}, Sacrifice this land: Look at the top six cards of your library. You may reveal a Bat, Bird, Mouse, or Rabbit card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Dawn

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Return all creature cards with power 2 or less from your graveyard to your hand.

Dusk

Destroy all creatures with power 3 or greater.

Dusk // Dawn

Molten Gatekeeper

Whenever another creature you control enters, this creature deals 1 damage to each opponent.
Unearth {R} ({R}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Remembrance

Whenever a nontoken creature you control dies, you may search your library for a card with the same name as that creature, reveal it, put it into your hand, then shuffle.

Sacred Foundry

({T}: Add {R} or {W}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Raise the Past

Return all creature cards with mana value 2 or less from your graveyard to the battlefield.

Clifftop Retreat

This land enters tapped unless you control a Mountain or a Plains.
{T}: Add {R} or {W}.

Witty Roastmaster

Alliance — Whenever another creature you control enters, this creature deals 1 damage to each opponent.

Exotic Orchard

Anointed Procession

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Enduring Innocence

Lifelink
Whenever one or more other creatures you control with power 2 or less enter, draw a card. This ability triggers only once each turn.
When Enduring Innocence dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Eiganjo, Seat of the Empire

{T}: Add {W}.
Channel — {2}{W}, Discard this card: It deals 4 damage to target attacking or blocking creature. This ability costs {1} less to activate for each legendary creature you control.