Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Electrodominance

Electrodominance deals X damage to any target. You may cast a spell with mana value X or less from your hand without paying its mana cost.

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Molten-Core Maestro

Menace
Opus — Whenever you cast an instant or sorcery spell, put a +1/+1 counter on this creature. If five or more mana was spent to cast that spell, add an amount of {R} equal to this creature's power.

Hostility

Haste
If a spell you control would deal damage to an opponent, prevent that damage. Create a 3/1 red Elemental Shaman creature token with haste for each 1 damage prevented this way.
When Hostility is put into a graveyard from anywhere, shuffle it into its owner's library.

Erebos's Intervention

Choose one —
• Target creature gets -X/-X until end of turn. You gain X life.
• Exile up to twice X target cards from graveyards.

Diabolic Revelation

Search your library for up to X cards, put those cards into your hand, then shuffle.

Fated Firepower

Flash
This enchantment enters with X fire counters on it.
If a source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus an amount of damage equal to the number of fire counters on this enchantment instead.

Shattering Pulse

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Destroy target artifact.

Arcane Signet

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

Dregs of Sorrow

Destroy X target nonblack creatures. Draw X cards.

Gwenom, Remorseless

Deathtouch, lifelink
Whenever Gwenom attacks, until end of turn, you may look at the top card of your library any time and you may play cards from the top of your library. If you cast a spell this way, pay life equal to its mana value rather than pay its mana cost.

Ad Nauseam

Reveal the top card of your library and put that card into your hand. You lose life equal to its mana value. You may repeat this process any number of times.

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 this enchantment. You may cast any number of the copies without paying their mana costs.

Fanning the Flames

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Fanning the Flames deals X damage to any target.

Disintegrate

Disintegrate deals X damage to any target. If it's a creature, it can't be regenerated this turn, and if it would die this turn, exile it instead.

Devil's Play

Devil's Play deals X damage to any target.
Flashback {X}{R}{R}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Fall of the Titans

Surge {X}{R} (You may cast this spell for its surge cost if you or a teammate has cast another spell this turn.)
Fall of the Titans deals X damage to each of up to two targets.

Reiterate

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Copy target instant or sorcery spell. You may choose new targets for the copy.

Exotic Orchard

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

Searing Touch

Buyback {4} (You may pay an additional {4} as you cast this spell. If you do, put this card into your hand as it resolves.)
Searing Touch deals 1 damage to any target.

Sol Ring

Fellwar Stone

Finale of Promise

You may cast up to one target instant card and/or up to one target sorcery card from your graveyard each with mana value X or less without paying their mana costs. If a spell cast this way would be put into your graveyard, exile it instead. If X is 10 or more, copy each of those spells twice. You may choose new targets for the copies.

Disturbed Burial

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Return target creature card from your graveyard to your hand.