When Abdel Adrian, Gorion's Ward enters the battlefield, exile any number of other nonland permanents you control until Abdel Adrian leaves the battlefield. Create a 1/1 white Soldier creature token for each permanent exiled this way.

Choose a Background (You can have a Background as a second commander.)

Activated abilities of creatures you control cost {X} less to activate, where X is Agatha of the Vile Cauldron's power. This effect can't reduce the mana in that cost to less than one mana.

{4}{R}{G}: Other creatures you control get +1/+1 and gain trample and haste until end of turn.

Balduvian Hydra enters the battlefield with X +1/+0 counters on it.

Remove a +1/+0 counter from Balduvian Hydra: Prevent the next 1 damage that would be dealt to Balduvian Hydra this turn.

{R}{R}{R}: Put a +1/+0 counter on Balduvian Hydra. Activate only during your upkeep.

Benevolent Hydra enters the battlefield with X +1/+1 counters on it.

If one or more +1/+1 counters would be put on another creature you control, that many plus one +1/+1 counters are put on it instead.

{T}, Remove a +1/+1 counter from Benevolent Hydra: Put a +1/+1 counter on another target creature you control.

Up to one target creature gets -X/-X until end of turn. If X is 5 or more, return a creature card with mana value X or less from your graveyard to the battlefield tapped.

When Bladecoil Serpent enters the battlefield, for each {U}{U} spent to cast it, draw a card.

When Bladecoil Serpent enters the battlefield, for each {B}{B} spent to cast it, each opponent discards a card.

When Bladecoil Serpent enters the battlefield, for each {R}{R} spent to cast it, it gets +1/+0 and gains trample and haste until end of turn.

More Than Meets the Eye {1}{R}{G} (You may cast this card converted for {1}{R}{G}.)

Other nontoken artifact creatures and Vehicles you control have modular 1. (They enter the battlefield with an additional +1/+1 counter on them. When they die, you may put their +1/+1 counters on target artifact creature.)

Whenever you put one or more +1/+1 counters on Blaster, convert it.

Modular 3

{X}, {T}: Move X +1/+1 counters from Blaster onto another target artifact. That artifact gains haste until end of turn. If Blaster has no +1/+1 counters on it, convert it. Activate only as a sorcery.

{X}: Crypt Rats deals X damage to each creature and each player. Spend only black mana on X.

Whenever a creature an opponent controls attacks one of your opponents, double its power until end of turn.

{X}{X}{R}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)

When Death Kiss becomes monstrous, goad up to X target creatures your opponents control.

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

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

Choose X. You may choose the same mode more than once.

• Each player sacrifices a nonartifact creature.

• Create a 3/3 black Dalek artifact creature token with menace.

• Each opponent discards a card.

Converge -- Gain control of target creature if its power is less than or equal to the number of colors of mana spent to cast this spell.

Grenzo, Dungeon Warden enters the battlefield with X +1/+1 counters on it.

{2}: Put the bottom card of your library into your graveyard. If it's a creature card with power less than or equal to Grenzo's power, put it onto the battlefield.

Haldir, Lórien Lieutenant enters the battlefield with X +1/+1 counters on it.

Vigilance

{5}{G}: Until end of turn, other Elves you control gain vigilance and get +1/+1 for each +1/+1 counter on Haldir.

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.

Heroic -- Whenever you cast a spell that targets Hero of Leina Tower, you may pay {X}. If you do, put X +1/+1 counters on Hero of Leina Tower.

Each legendary creature you control gets +1/+1 for each other legendary creature you control.

{X}, {T}: Look at the top X cards of your library. You may reveal a legendary creature card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

{X}{B/P}: Remove up to X counters from target permanent. For each counter removed this way, Hex Parasite gets +1/+0 until end of turn. ({B/P} can be paid with either {B} or 2 life.)

For each creature, its controller sacrifices it unless they pay X life.

Choose one. If you control a commander as you cast this spell, you may choose both.

• Breathe Flame -- Klauth's Will deals X damage to each creature without flying.

• Smash Relics -- Destroy up to X target artifacts and/or enchantments.

Knickknack Ouphe enters the battlefield with X +1/+1 counters on it.

When Knickknack Ouphe enters the battlefield, reveal the top X cards of your library. You may put any number of Aura cards with mana value X or less from among them onto the battlefield. Then put all cards revealed this way that weren't put onto the battlefield on the bottom of your library in a random order.

{X}, Discard a card with mana value X: Knollspine Invocation deals X damage to any target.

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

{1}{G}: Regenerate Krakilin.

If you control two or more other lands, Lair of the Hydra enters the battlefield tapped.

{T}: Add {G}.

{X}{G}: Until end of turn, Lair of the Hydra becomes an X/X green Hydra creature. It's still a land. X can't be 0.

Lava Burst deals X damage to any target. If Lava Burst would deal damage to a creature, that damage can't be prevented or dealt instead to another permanent or player.

Lavaclaw Reaches enters the battlefield tapped.

{T}: Add {B} or {R}.

{1}{B}{R}: Until end of turn, Lavaclaw Reaches becomes a 2/2 black and red Elemental creature with "{X}: This creature gets +X/+0 until end of turn." It's still a land.

Lavalanche deals X damage to target player or planeswalker and each creature that player or that planeswalker's controller controls.

Exile the top card of each player's library. Until the end of your next turn, you may play those cards, and mana of any type can be spent to cast them.

Flashback {2}{B}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Trample, haste

Lightning Serpent enters the battlefield with X +1/+0 counters on it.

At the beginning of the end step, sacrifice Lightning Serpent.

Mill X cards. Target player loses 2 life for each creature card put into your graveyard this way.

Return X target cards with different mana values from your graveyard to your hand. If eight or more cards were returned to your hand this way, your life total becomes equal to your starting life total. Exile Long Rest.

Target creature gets +X/+X until end of turn. Create a 1/1 green and white Citizen creature token.

Flying

Whenever you cast a noncreature spell, create an X/X red Dragon Illusion creature token with flying and haste, where X is the amount of mana spent to cast that spell. Exile that token at the beginning of the next end step.

Trample

When Marut enters the battlefield, if mana from a Treasure was spent to cast it, create a Treasure token for each mana from a Treasure spent to cast it. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

As Neverwinter Hydra enters the battlefield, roll X d6. It enters with a number of +1/+1 counters on it equal to the total of those results.

Trample

Ward {4} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {4}.)

You may exile a green card with mana value X from your hand rather than pay this spell's mana cost.

You gain X life.

At the beginning of combat on your turn, you may pay {X}{X}. When you do, distribute X +1/+1 counters among any number of target Elves.

Partner (You can have two commanders if both have partner.)

This spell costs {X} less to cast, where X is the total mana value of noncreature enchantments you control.

Trample

{1}{G}, Sacrifice another enchantment: Nyxborn Behemoth gains indestructible until end of turn.

Omarthis, Ghostfire Initiate enters the battlefield with X +1/+1 counters on it.

Whenever you put one or more +1/+1 counters on another colorless creature, you may put a +1/+1 counter on Omarthis.

When Omarthis dies, manifest a number of cards from the top of your library equal to the number of counters on it.

Return target card from your graveyard to your hand. Put up to one other target card from your graveyard on top of your library. Exile Once and Future.

Adamant -- If at least three green mana was spent to cast this spell, instead return those cards to your hand and exile Once and Future.

X can't be greater than the number of players in the game.

Reveal cards from the top of your library until you reveal X land cards. Put those land cards onto the battlefield tapped and the rest on the bottom of your library in a random order.

Flying, trample

When Orcus, Prince of Undeath enters the battlefield, choose one --

• Each other creature gets -X/-X until end of turn. You lose X life.

• Return up to X target creature cards with total mana value X or less from your graveyard to the battlefield. They gain haste until end of turn.

Orochi Hatchery enters the battlefield with X charge counters on it.

{5}, {T}: Create a 1/1 green Snake creature token for each charge counter on Orochi Hatchery.

Flying

{3}: Paragon of Modernity gets +1/+1 until end of turn. If exactly three colors of mana were spent to activate this ability, put a +1/+1 counter on it instead.

{X}, Sacrifice Pernicious Deed: Destroy each artifact, creature, and enchantment with mana value X or less.

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."

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

When Polukranos, World Eater becomes monstrous, it deals X damage divided as you choose among any number of target creatures your opponents control. Each of those creatures deals damage equal to its power to Polukranos.

If Primeval Spawn would enter the battlefield and it wasn't cast or no mana was spent to cast it, exile it instead.

Vigilance, trample, lifelink

When Primeval Spawn leaves the battlefield, exile the top ten cards of your library. You may cast any number of spells with total mana value 10 or less from among them without paying their mana costs.

Converge -- Prism Array enters the battlefield with a crystal counter on it for each color of mana spent to cast it.

Remove a crystal counter from Prism Array: Tap target creature.

{W}{U}{B}{R}{G}: Scry 3. (Look at the top three cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)

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

Destroy up to X target artifacts. If X is 5 or more, for each artifact destroyed this way, create a token that's a copy of it. Those tokens gain haste. Exile them at the beginning of the next end step.

Menace (This creature can't be blocked except by two or more creatures.)

When Relentless Dead dies, you may pay {B}. If you do, return it to its owner's hand.

When Relentless Dead dies, you may pay {X}. If you do, return another target Zombie creature card with mana value X from your graveyard to the battlefield.

Whenever you cast a creature spell with mana value 5 or greater, that creature enters the battlefield with X additional +1/+1 counters on it, where X is its mana value minus 4.

Creatures you control with three or more +1/+1 counters on them have haste.

{T}: Add {G}.

Enchant creature

Enchanted creature gets -X/-Y. If that creature is attacking, X is the number of snow lands defending player controls. Otherwise, X is the number of snow lands its controller controls. Y is equal to X or to enchanted creature's toughness minus 1, whichever is smaller.

First strike, haste

Sanctified Rules of Combat -- When Sycorax Commander enters the battlefield, each opponent faces a villainous choice -- That opponent discards all the cards in their hand, then draws that many cards minus one, or Sycorax Commander deals damage to that player equal to the number of cards in their hand.

Hexproof (This creature can't be the target of spells or abilities your opponents control.)

{3}{B}: Until end of turn, Xathrid Slyblade loses hexproof and gains first strike and deathtouch. (It deals combat damage before creatures without first strike. Any amount of damage it deals to a creature is enough to destroy it.)

{T}, Remove a counter from another permanent you control: Populate. Activate only as a sorcery. (Create a token that's a copy of a creature token you control.)

{T}, Sacrifice another creature: Proliferate. Activate only as a sorcery. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Double strike

Auras you control have exalted. (Whenever a creature you control attacks alone, it gets +1/+1 until end of turn for each instance of exalted among permanents you control.)