Mountain

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Lightning Helix

Lightning Helix deals 3 damage to any target and you gain 3 life.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Spell Snare

Supreme Verdict

This spell can't be countered.
Destroy all creatures.

Scalding Tarn

{T}, Pay 1 life, Sacrifice Scalding Tarn: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle.

Mana Leak

Counter target spell unless its controller pays {3}.

Plains

Deflecting Palm

The next time a source of your choice would deal damage to you this turn, prevent that damage. If damage is prevented this way, Deflecting Palm deals that much damage to that source's controller.

Sphinx's Revelation

Flooded Strand

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

Snapcaster Mage

Flash
When Snapcaster Mage enters, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)

Remand

Counter target spell. If that spell is countered this way, put it into its owner's hand instead of into that player's graveyard.
Draw a card.

Teferi, Time Raveler

Each opponent can cast spells only any time they could cast a sorcery.
+1: Until your next turn, you may cast sorcery spells as though they had flash.
−3: Return up to one target artifact, creature, or enchantment to its owner's hand. Draw a card.

Jace, the Mind Sculptor

+2: Look at the top card of target player's library. You may put that card on the bottom of that player's library.
0: Draw three cards, then put two cards from your hand on top of your library in any order.
−1: Return target creature to its owner's hand.
−12: Exile all cards from target player's library, then that player shuffles their hand into their library.

Island

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.

Steam Vents

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

Cryptic Command

Choose two —
• Counter target spell.
• Return target permanent to its owner's hand.
• Tap all creatures your opponents control.
• Draw a card.

Geist of Saint Traft

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Whenever Geist of Saint Traft attacks, create a 4/4 white Angel creature token with flying that's tapped and attacking. Exile that token at end of combat.

Hallowed Fountain

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

Shatter the Sky

Each player who controls a creature with power 4 or greater draws a card. Then destroy all creatures.

Sacred Foundry

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