Astral Cornucopia enters the battlefield with X charge counters on it. {T}: Choose a color. Add one mana of that color for each charge counter on Astral Cornucopia.

As Caged Sun enters the battlefield, choose a color. Creatures you control of the chosen color get +1/+1. Whenever a land's ability causes you to add one or more mana of the chosen color, add one additional mana of that color.

Lands you control have "{T}: Add one mana of any color." {T}: Add one mana of any color.

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}.

Fire Diamond enters the battlefield tapped. {T}: Add {R}.

{T}: Add three mana of any one color.

{1}, {T}: Add {R}{G}.

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.) Equip {0}

{2}, {T}: Copy target activated or triggered ability you control. You may choose new targets for the copy. {3}, {T}: Copy target instant or sorcery spell you control. You may choose new targets for the copy. {4}, {T}: Copy target permanent spell you control. (The copy becomes a token.)

Mana Vault doesn't untap during your untap step. At the beginning of your upkeep, you may pay {4}. If you do, untap Mana Vault. At the beginning of your draw step, if Mana Vault is tapped, it deals 1 damage to you. {T}: Add {C}{C}{C}.

Moss Diamond enters the battlefield tapped. {T}: Add {G}.

Red spells you cast cost {1} less to cast.

{T}: Add {C}{C}.

Equipped creature gets +1/+1. Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Equip {2}

Apocalypse Hydra enters the battlefield with X +1/+1 counters on it. If X is 5 or more, it enters the battlefield with an additional X +1/+1 counters on it. {1}{R}, Remove a +1/+1 counter from Apocalypse Hydra: It deals 1 damage to any target.

Endless One enters the battlefield with X +1/+1 counters on it.

When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.

Flying Whenever Flameblast Dragon attacks, you may pay {X}{R}. If you do, Flameblast Dragon deals X damage to any target.

When you cast this spell, reveal the top X cards of your library. You may put a nonland permanent card with mana value X or less from among them onto the battlefield. Then shuffle the rest into your library. Genesis Hydra enters the battlefield with X +1/+1 counters on it.

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

{X}{X}{1}: Destroy target noncreature artifact with mana value X.

Hangarback Walker enters the battlefield with X +1/+1 counters on it. When Hangarback Walker dies, create a 1/1 colorless Thopter artifact creature token with flying for each +1/+1 counter on Hangarback Walker. {1}, {T}: Put a +1/+1 counter on Hangarback Walker.

Hooded Hydra enters the battlefield with X +1/+1 counters on it. When Hooded Hydra dies, create a 1/1 green Snake creature token for each +1/+1 counter on it. Morph {3}{G}{G} As Hooded Hydra is turned face up, put five +1/+1 counters on it.

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.

{X}{X}{G}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.) When Hydra Broodmaster becomes monstrous, create X X/X green Hydra creature tokens.

When Imperial Recruiter enters the battlefield, search your library for a creature card with power 2 or less, reveal it, put it into your hand, then shuffle.

Protean Hydra enters the battlefield with X +1/+1 counters on it. If damage would be dealt to Protean Hydra, prevent that damage and remove that many +1/+1 counters from it. Whenever a +1/+1 counter is removed from Protean Hydra, put two +1/+1 counters on it at the beginning of the next end step.

Each creature you control with a mana ability gets +2/+2. Whenever a creature you control with a mana ability attacks, untap it. Whenever you cast a spell, if at least seven mana was spent to cast it, untap target creature. It gets +7/+7 and gains trample until end of turn.

Flying Whenever Savage Ventmaw attacks, add {R}{R}{R}{G}{G}{G}. Until end of turn, you don't lose this mana as steps and phases end.

Reach {X}{G}{G}: Silklash Spider deals X damage to each creature with flying.

Prowess If a source you control would deal noncombat damage to a creature an opponent controls, put that many -1/-1 counters on that creature instead.

Flying {2}: Steel Hellkite gets +1/+0 until end of turn. {X}: Destroy each nonland permanent with mana value X whose controller was dealt combat damage by Steel Hellkite this turn. Activate only once each turn.

Trample If damage would be dealt to another creature you control, prevent that damage. Put a +1/+1 counter on that creature for each 1 damage prevented this way. When Vigor is put into a graveyard from anywhere, shuffle it into its owner's library.

Trample Whenever you tap a land for mana, add one mana of any type that land produced. Whenever an opponent taps a land for mana, that land doesn't untap during its controller's next untap step.

Walking Ballista enters the battlefield with X +1/+1 counters on it. {4}: Put a +1/+1 counter on Walking Ballista. Remove a +1/+1 counter from Walking Ballista: It deals 1 damage to any target.

Reach Wren's Run Hydra enters the battlefield with X +1/+1 counters on it. Reinforce X—{X}{G}{G} ({X}{G}{G}, Discard this card: Put X +1/+1 counters on target creature.)

{3}{R}{R}: Untap all creatures you control. After this main phase, there is an additional combat phase followed by an additional main phase. Activate only as a sorcery.

Creatures you control have hexproof. {1}{G}: Regenerate target creature. (The next time it would be destroyed, instead tap it, remove it from combat, and heal all damage on it.)

As Frontier Siege enters the battlefield, choose Khans or Dragons. • Khans — At the beginning of each of your main phases, add {G}{G}. • Dragons — Whenever a creature with flying enters the battlefield under your control, you may have it fight target creature you don't control.

At the beginning of your end step, if you control a creature with power 4 or greater, exile the top card of your library. You may play that card until you exile another card with Furious Rise.

Whenever you cast a permanent spell with a mana cost that contains {X}, double the value of X. Whenever you cast an instant or sorcery spell or activate an ability, if that spell's mana cost or that ability's activation cost contains {X}, copy that spell or ability. You may choose new targets for the copy.

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.

Copy target instant or sorcery spell you control. If this spell was cast from a graveyard, copy that spell twice instead. You may choose new targets for the copies. Flashback {3}{R}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

({G/P} can be paid with either {G} or 2 life.) Put target card from a graveyard on top of its owner's library.

Choose one — • Draw cards equal to the greatest power among non-Human creatures you control. • Non-Human creatures you control get +3/+3 until end of turn.

When Aether Hub enters the battlefield, you get {E} (an energy counter). {T}: Add {C}. {T}, Pay {E}: Add one mana of any color.

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

({T}: Add {R} or {G}.) Cinder Glade enters the battlefield tapped unless you control two or more basic lands.

Copperline Gorge enters the battlefield tapped unless you control two or fewer other lands. {T}: Add {R} or {G}.

({T}: Add {G}.)

As Game Trail enters the battlefield, you may reveal a Mountain or Forest card from your hand. If you don't, Game Trail enters the battlefield tapped. {T}: Add {R} or {G}.

{T}: Add {C}. {3}, {T}, Sacrifice Haunted Fengraf: Return a creature card at random from your graveyard to your hand.

({T}: Add {R}.)

Raging Ravine enters the battlefield tapped. {T}: Add {R} or {G}. {2}{R}{G}: Until end of turn, Raging Ravine becomes a 3/3 red and green Elemental creature with "Whenever this creature attacks, put a +1/+1 counter on it." It's still a land.

Rootbound Crag enters the battlefield tapped unless you control a Mountain or a Forest. {T}: Add {R} or {G}.

Rugged Highlands enters the battlefield tapped. When Rugged Highlands enters the battlefield, you gain 1 life. {T}: Add {R} or {G}.

Temple of Abandon enters the battlefield tapped. When Temple of Abandon enters the battlefield, scry 1. {T}: Add {R} or {G}.

Vivid Grove enters the battlefield tapped with two charge counters on it. {T}: Add {G}. {T}, Remove a charge counter from Vivid Grove: Add one mana of any color.

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.

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.

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

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.

Demonfire deals X damage to any target. If a creature dealt damage this way would die this turn, exile it instead. Hellbent — If you have no cards in hand, this spell can't be countered and the damage can't be prevented.

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.)

Create X X/X green Ooze creature tokens.

When you cast your next instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy. Raid — If you attacked this turn, when you cast your next instant or sorcery spell this turn, copy that spell an additional time. You may choose new targets for the copy.

Destroy X target artifacts and/or creatures. For each permanent destroyed this way, its controller reveals cards from the top of their library until an artifact or creature card is revealed and exiles that card. Those players put the exiled cards onto the battlefield, then shuffle.

Target creature you control gets +X/+X until end of turn. Then it fights up to one target creature you don't control.

Choose one — • Create an X/1 red Elemental creature token with trample and haste. Sacrifice it at the beginning of the next end step. • Purphoros's Intervention deals twice X damage to target creature or planeswalker.

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

Destroy X target artifacts. Create X 2/2 red Gremlin creature tokens.

Return any number of cards with different mana values from your graveyard to your hand. Put Seasons Past on the bottom of its owner's library.

Destroy all creatures with flying.

Manifest the top card of your library, then put X +1/+1 counters on it. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)