Mountain

Chandra Ablaze

+1: Discard a card. If a red card is discarded this way, Chandra Ablaze deals 4 damage to any target.
−2: Each player discards their hand, then draws three cards.
−7: Cast any number of red instant and/or sorcery cards from your graveyard without paying their mana costs.

Blue Sun's Twilight

Gain control of target creature with mana value X or less. If X is 5 or more, create a token that's a copy of that creature.

Artificer Class

(Gain the next level as a sorcery to add its ability.)
The first artifact spell you cast each turn costs {1} less to cast.
{1}{U}: Level 2
When this Class becomes level 2, reveal cards from the top of your library until you reveal an artifact card. Put that card into your hand and the rest on the bottom of your library in a random order.
{5}{U}: Level 3
At the beginning of your end step, create a token that's a copy of target artifact you control.

Izzet Guildgate

Izzet Guildgate enters tapped.
{T}: Add {U} or {R}.

Cascade Bluffs

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

Traveler's Amulet

{1}, Sacrifice Traveler's Amulet: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.

Chandra, Flame's Catalyst

+1: Chandra, Flame's Catalyst deals 3 damage to each opponent.
−2: You may cast target red instant or sorcery card from your graveyard. If that spell would be put into your graveyard, exile it instead.
−8: Discard your hand, then draw seven cards. Until end of turn, you may cast spells from your hand without paying their mana costs.

Arcane Signet

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

Primal Wellspring

(Transforms from Primal Amulet.)
{T}: Add one mana of any color. When that mana is spent to cast an instant or sorcery spell, copy that spell and you may choose new targets for the copy.

Primal Amulet

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, put a charge counter on Primal Amulet. Then if there are four or more charge counters on it, you may remove those counters and transform it.

Primal Amulet // Primal Wellspring

Amulet of Safekeeping

Whenever you become the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.
Creature tokens get -1/-0.

Counterspell

Twinning Staff

If you would copy a spell one or more times, instead copy it that many times plus an additional time. You may choose new targets for the additional copy.
{7}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy.

Call Forth the Tempest

Cascade, cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom of your library in a random order. Then do it again.)
Call Forth the Tempest deals damage to each creature your opponents control equal to the total mana value of other spells you've cast this turn.

Bedlam Reveler

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
Prowess
When Bedlam Reveler enters, discard your hand, then draw three cards.

Catalyst Stone

Flashback costs you pay cost {2} less.
Flashback costs your opponents pay cost {2} more.

Beacon Bolt

Beacon Bolt deals damage to target creature equal to the total number of instant and sorcery cards you own in exile and in your graveyard.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Assert Authority

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Act on Impulse

Exile the top three cards of your library. Until end of turn, you may play those cards. (If you cast a spell this way, you still pay its costs. You can play a land this way only if you have an available land play remaining.)

Arcane Bombardment

Whenever you cast your first instant or sorcery spell each turn, exile an instant or sorcery card at random from your graveyard. Then copy each card exiled with Arcane Bombardment. You may cast any number of the copies without paying their mana costs.

Sol Ring

Blackblade Reforged

Equipped creature gets +1/+1 for each land you control.
Equip legendary creature {3}
Equip {7}

Galazeth Prismari

Flying
When Galazeth Prismari enters, create a Treasure token.
Artifacts you control have "{T}: Add one mana of any color. Spend this mana only to cast an instant or sorcery spell."

Blue Sun's Zenith

Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.

Battlefield Thaumaturge

Each instant and sorcery spell you cast costs {1} less to cast for each creature it targets.
Heroic — Whenever you cast a spell that targets Battlefield Thaumaturge, Battlefield Thaumaturge gains hexproof until end of turn.

Arwen's Gift

This spell costs {1} less to cast if you control two or more legendary creatures.
Scry 2, then draw two cards.