By Force

Comet Storm

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)
Choose any target, then choose another target for each time this spell was kicked. Comet Storm deals X damage to each of them.

Rosheen, Roaring Prophet

When Rosheen, Roaring Prophet enters, mill six cards. You may put a card with {X} in its mana cost from among them into your hand.
{T}: Reveal any number of cards with {X} in their mana cost in your hand. Add {C}{C} for each card revealed this way. Spend this mana only on costs that contain {X}.

Commune with Lava

Exile the top X cards of your library. Until the end of your next turn, you may play those cards.

Awaken the Woods

Create X 1/1 green Forest Dryad land creature tokens. (They're affected by summoning sickness.)

Blaze

Sporocyst

Ravenous (This creature enters with X +1/+1 counters on it. If X is 5 or more, draw a card when it enters.)
Defender
Spore Chimney — When Sporocyst enters, search your library for up to X basic land cards, put them onto the battlefield tapped, then shuffle.

Solphim, Mayhem Dominus

If a source you control would deal noncombat damage to an opponent or a permanent an opponent controls, it deals double that damage to that player or permanent instead.
{1}{R/P}{R/P}, Discard two cards: Put an indestructible counter on Solphim, Mayhem Dominus. ({R/P} can be paid with either {R} or 2 life.)

Fireball

This spell costs {1} more to cast for each target beyond the first.
Fireball deals X damage divided evenly, rounded down, among any number of targets.

Chord of Calling

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Reap the Past

Return X cards at random from your graveyard to your hand. Exile Reap the Past.

Animist's Awakening

Reveal the top X cards of your library. Put all land cards from among them onto the battlefield tapped and the rest on the bottom of your library in a random order.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, untap those lands.

Delete

Delete deals X damage to each nonartifact creature and each player.

Fiery Emancipation

If a source you control would deal damage to a permanent or player, it deals triple that damage to that permanent or player instead.

Earthquake

Earthquake deals X damage to each creature without flying and each player.

Crackle with Power

Crackle with Power deals five times X damage to each of up to X targets.

Torbran, Thane of Red Fell

If a red source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 2 instead.

Nahiri's Lithoforming

Sacrifice X lands. For each land sacrificed this way, draw a card. You may play X additional lands this turn. Lands you control enter tapped this turn.

Goblin Anarchomancer

Each spell you cast that's red or green costs {1} less to cast.

Seeker of Skybreak

Llanowar Elves

Hell to Pay

Hell to Pay deals X damage to target creature. Create a number of tapped Treasure tokens equal to the amount of excess damage dealt to that creature this way.

Worldsoul's Rage

Worldsoul's Rage deals X damage to any target. Put up to X land cards from your hand and/or graveyard onto the battlefield tapped.

Banefire

Banefire deals X damage to any target.
If X is 5 or more, this spell can't be countered and the damage can't be prevented.

Burn from Within

Burn from Within deals X damage to any target. If a creature is dealt damage this way, it loses indestructible until end of turn. If that creature would die this turn, exile it instead.

Birds of Paradise

Magus of the Candelabra

Pest Infestation

Destroy up to X target artifacts and/or enchantments. Create twice X 1/1 black and green Pest creature tokens with "When this creature dies, you gain 1 life."

Fyndhorn Elves

Crater's Claws

Crater's Claws deals X damage to any target.
Ferocious — Crater's Claws deals X plus 2 damage instead if you control a creature with power 4 or greater.

Clan Defiance

Choose one or more —
• Clan Defiance deals X damage to target creature with flying.
• Clan Defiance deals X damage to target creature without flying.
• Clan Defiance deals X damage to target player or planeswalker.

Elvish Mystic

Jaya's Immolating Inferno

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Jaya's Immolating Inferno deals X damage to each of up to three targets.

Nyxbloom Ancient

Trample
If you tap a permanent for mana, it produces three times as much of that mana instead.

Finale of Devastation

Search your library and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.

Shatterskull, the Hammer Pass

As Shatterskull, the Hammer Pass enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {R}.

Shatterskull Smashing

Shatterskull Smashing deals X damage divided as you choose among up to two target creatures and/or planeswalkers. If X is 6 or more, Shatterskull Smashing deals twice X damage divided as you choose among them instead.

Shatterskull Smashing // Shatterskull, the Hammer Pass

Elementalist's Palette

Whenever you cast a spell with {X} in its mana cost, put two charge counters on Elementalist's Palette.
{T}: Add one mana of any color.
{T}: Add {C} for each charge counter on Elementalist's Palette. Spend this mana only on costs that contain {X}.

Spiteful Banditry

When Spiteful Banditry enters, it deals X damage to each creature.
Whenever one or more creatures your opponents control die, you create a Treasure token. This ability triggers only once each turn.

Detonate

Destroy target artifact with mana value X. It can't be regenerated. Detonate deals X damage to that artifact's controller.