Mountain

Esper Sentinel

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

Galvanic Discharge

Choose target creature or planeswalker. You get {E}{E}{E} (three energy counters), then you may pay any amount of {E}. Galvanic Discharge deals that much damage to that permanent.

Elegant Parlor

({T}: Add {R} or {W}.)
Elegant Parlor enters tapped.
When Elegant Parlor enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

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.

Tear

Destroy target enchantment.
Fuse (You may cast one or both halves of this card from your hand.)

Wear

Destroy target artifact.
Fuse (You may cast one or both halves of this card from your hand.)

Wear // Tear

Arena of Glory

Arena of Glory enters tapped unless you control a Mountain.
{T}: Add {R}.
{R}, {T}, Exert Arena of Glory: Add {R}{R}. If that mana is spent on a creature spell, it gains haste until end of turn. (An exerted permanent won't untap during your next untap step.)

Meltdown

Destroy each artifact with mana value X or less.

Damping Sphere

If a land is tapped for two or more mana, it produces {C} instead of any other type and amount.
Each spell a player casts costs {1} more to cast for each other spell that player has cast this turn.

Thraben Charm

Choose one —
• Thraben Charm deals damage equal to twice the number of creatures you control to target creature.
• Destroy target enchantment.
• Exile any number of target players' graveyards.

Plains

Arid Mesa

{T}, Pay 1 life, Sacrifice Arid Mesa: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Whipflare

Whipflare deals 2 damage to each nonartifact creature.

Strict Proctor

Flying
Whenever a permanent entering causes a triggered ability to trigger, counter that ability unless its controller pays {2}.

Rest in Peace

When Rest in Peace enters, exile all graveyards.
If a card or token would be put into a graveyard from anywhere, exile it instead.

Doorkeeper Thrull

Flash
Flying
Artifacts and creatures entering don't cause abilities to trigger.

Phlage, Titan of Fire's Fury

When Phlage enters, sacrifice it unless it escaped.
Whenever Phlage enters or attacks, it deals 3 damage to any target and you gain 3 life.
Escape—{R}{R}{W}{W}, Exile five other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)

Sacred Foundry

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

Wrath of the Skies

You get X {E} (energy counters), then you may pay any amount of {E}. Destroy each artifact, creature, and enchantment with mana value less than or equal to the amount of {E} paid this way.