You may have Altered Ego enter the battlefield as a copy of any creature on the battlefield, except it enters with X additional +1/+1 counters on it.
0 /
0
{X}{X}{X}
Astral Cornucopia
Artifact
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.
{X}{U}{U}{U}
Blue Sun's Zenith
Instant
Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.
{1}{G}{U}
Bred for the Hunt
Enchantment
Whenever a creature you control with a +1/+1 counter on it deals combat damage to a player, you may draw a card.
{1}{U}{U}
Callaphe, Beloved of the Sea
Legendary Enchantment Creature - Demigod
Callaphe's power is equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
Creatures and enchantments you control have "Spells your opponents cast that target this permanent cost {1} more to cast."
* /
3
{2}{G}
Colossal Majesty
Enchantment
At the beginning of your upkeep, if you control a creature with power 4 or greater, draw a card.
--
Command Tower
Land
{T}: Add one mana of any color in your commander's color identity.
--
Coral Atoll
Land
Coral Atoll enters the battlefield tapped.
When Coral Atoll enters the battlefield, sacrifice it unless you return an untapped Island you control to its owner's hand.
{T}: Add {C}{U}.
{X}{B}{B}
Death Denied
Instant - Arcane
Return X target creature cards from your graveyard to your hand.
{X}{B}
Death Wind
Instant
Target creature gets -X/-X until end of turn.
--
Dimir Aqueduct
Land
Dimir Aqueduct enters the battlefield tapped.
When Dimir Aqueduct enters the battlefield, return a land you control to its owner's hand.
{T}: Add {U}{B}.
--
Dismal Backwater
Land
Dismal Backwater enters the battlefield tapped.
When Dismal Backwater enters the battlefield, you gain 1 life.
{T}: Add {U} or {B}.
{2}{G}{G}
Domesticated Hydra
Creature - Hydra
{X}{G}{G}{G}: Monstrosity X. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)
As long as Domesticated Hydra is monstrous, it has trample.
3 /
3
{4}{G}
Doubling Season
Enchantment
If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.
--
Dreadship Reef
Land
{T}: Add {C}.
{1}, {T}: Put a storage counter on Dreadship Reef.
{1}, Remove X storage counters from Dreadship Reef: Add X mana in any combination of {U} and/or {B}.
{2}{G}
Evolution Sage
Creature - Elf Druid
Landfall -- Whenever a land enters the battlefield under your control, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
3 /
2
{2}{G}{G}{U}{U}
Experiment Kraj
Legendary Creature - Ooze Mutant
Experiment Kraj has all activated abilities of each other creature with a +1/+1 counter on it.
{T}: Put a +1/+1 counter on target creature.
4 /
6
{X}{X}{G}{G}
Exponential Growth
Sorcery
Until end of turn, double target creature's power X times.
{X}{G}
Feral Hydra
Creature - Hydra Beast
Feral Hydra enters the battlefield with X +1/+1 counters on it.
{3}: Put a +1/+1 counter on Feral Hydra. Any player may activate this ability.
0 /
0
{X}{U}{U}
Finale of Revelation
Sorcery
Draw X cards. If X is 10 or more, instead shuffle your graveyard into your library, draw X cards, untap up to five lands, and you have no maximum hand size for the rest of the game.
Exile Finale of Revelation.
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
{2}{U}{U}
Fuel for the Cause
Instant
Counter target spell, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
{3}{G}{G}{G}
Gargos, Vicious Watcher
Legendary Creature - Hydra
Vigilance
Hydra spells you cast cost {4} less to cast.
Whenever a creature you control becomes the target of a spell, Gargos, Vicious Watcher fights up to one target creature you don't control.
8 /
7
{2}{G}
Garruk's Uprising
Enchantment
When Garruk's Uprising enters the battlefield, if you control a creature with power 4 or greater, draw a card.
Creatures you control have trample. (They can deal excess combat damage to the player or planeswalker they're attacking.)
Whenever a creature with power 4 or greater enters the battlefield under your control, draw a card.
{X}{G}{G}
Genesis Hydra
Creature - Plant Hydra
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.
0 /
0
{2}{G}
Gift of Paradise
Enchantment - Aura
Enchant land
When Gift of Paradise enters the battlefield, you gain 3 life.
Enchanted land has "{T}: Add two mana of any one color."
--
Golgari Rot Farm
Land
Golgari Rot Farm enters the battlefield tapped.
When Golgari Rot Farm enters the battlefield, return a land you control to its owner's hand.
{T}: Add {B}{G}.
{1}{B}{G}
Grakmaw, Skyclave Ravager
Legendary Creature - Hydra Horror
Grakmaw, Skyclave Ravager enters the battlefield with three +1/+1 counters on it.
Whenever another creature you control dies, if it had a +1/+1 counter on it, put a +1/+1 counter on Grakmaw.
When Grakmaw dies, create an X/X black and green Hydra creature token, where X is the number of +1/+1 counters on Grakmaw.
0 /
0
--
Guildless Commons
Land
Guildless Commons enters the battlefield tapped.
When Guildless Commons enters the battlefield, return a land you control to its owner's hand.
{T}: Add {C}{C}.
{1}{G}{U}
Hadana's Climb
Legendary Enchantment
At the beginning of combat on your turn, put a +1/+1 counter on target creature you control. Then if that creature has three or more +1/+1 counters on it, transform Hadana's Climb.
--
Winged Temple of Orazca
Legendary Land
(Transforms from Hadana's Climb.)
{T}: Add one mana of any color.
{1}{G}{U}, {T}: Target creature you control gains flying and gets +X/+X until end of turn, where X is its power.
--
Halimar Depths
Land
Halimar Depths enters the battlefield tapped.
When Halimar Depths enters the battlefield, look at the top three cards of your library, then put them back in any order.
{T}: Add {U}.
{3}{U}
Herald of Secret Streams
Creature - Merfolk Warrior
Creatures you control with +1/+1 counters on them can't be blocked.
2 /
3
{3}{G}{G}
Heroes' Bane
Creature - Hydra
Heroes' Bane enters the battlefield with four +1/+1 counters on it.
{2}{G}{G}: Put X +1/+1 counters on Heroes' Bane, where X is its power.
0 /
0
{1}{B}{B}
Hissing Miasma
Enchantment
Whenever a creature attacks you, its controller loses 1 life.
{X}{G}{G}
Hooded Hydra
Creature - Snake Hydra
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.
0 /
0
{X}{G}
Hungering Hydra
Creature - Hydra
Hungering Hydra enters the battlefield with X +1/+1 counters on it.
Hungering Hydra can't be blocked by more than one creature.
Whenever Hungering Hydra is dealt damage, put that many +1/+1 counters on it. (It must survive the damage to get the counters.)
0 /
0
{4}{G}{G}
Hydra Broodmaster
Creature - Hydra
{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.
7 /
7
{4}{G}{G}
Hydra Omnivore
Creature - Hydra
Whenever Hydra Omnivore deals combat damage to an opponent, it deals that much damage to each other opponent.
8 /
8
{2}{G}
Hydra's Growth
Enchantment - Aura
Enchant creature
When Hydra's Growth enters the battlefield, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.
{X}{G}{U}
Hydroid Krasis
Creature - Jellyfish Hydra Beast
When you cast this spell, you gain half X life and draw half X cards. Round down each time.
Flying, trample
Hydroid Krasis enters the battlefield with X +1/+1 counters on it.
0 /
0
{7}{B}{B}
In Garruk's Wake
Sorcery
Destroy all creatures you don't control and all planeswalkers you don't control.
{1}{G}
Incubation Druid
Creature - Elf Druid
{T}: Add one mana of any type that a land you control could produce. If Incubation Druid has a +1/+1 counter on it, add three mana of that type instead.
{3}{G}{G}: Adapt 3. (If this creature has no +1/+1 counters on it, put three +1/+1 counters on it.)
0 /
2
{3}{G}{G}
Ironscale Hydra
Creature - Hydra
If a creature would deal combat damage to Ironscale Hydra, prevent that damage and put a +1/+1 counter on Ironscale Hydra.
5 /
5
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
{2}{G}
Jiang Yanggu, Wildcrafter
Legendary Planeswalker - Yanggu
Each creature you control with a +1/+1 counter on it has "{T}: Add one mana of any color."
-1: Put a +1/+1 counter on target creature.
L:
3
--
Jungle Basin
Land
Jungle Basin enters the battlefield tapped.
When Jungle Basin enters the battlefield, sacrifice it unless you return an untapped Forest you control to its owner's hand.
{T}: Add {C}{G}.
--
Jungle Hollow
Land
Jungle Hollow enters the battlefield tapped.
When Jungle Hollow enters the battlefield, you gain 1 life.
{T}: Add {B} or {G}.
--
Jwar Isle Refuge
Land
Jwar Isle Refuge enters the battlefield tapped.
When Jwar Isle Refuge enters the battlefield, you gain 1 life.
{T}: Add {U} or {B}.
--
Llanowar Reborn
Land
Llanowar Reborn enters the battlefield tapped.
{T}: Add {G}.
Graft 1 (This land enters the battlefield with a +1/+1 counter on it. Whenever a creature enters the battlefield, you may move a +1/+1 counter from this land onto it.)
{3}{G}
Longshot Squad
Creature - Dog Archer
Outlast {1}{G} ({1}{G}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has reach. (A creature with reach can block creatures with flying.)
3 /
3
--
Lotus Field
Land
Hexproof
Lotus Field enters the battlefield tapped.
When Lotus Field enters the battlefield, sacrifice two lands.
{T}: Add three mana of any one color.
{X}{U}{U}{U}
Lullmage's Domination
Sorcery
This spell costs {3} less to cast if it targets a creature whose controller has eight or more cards in their graveyard.
Gain control of target creature with mana value X.
{2}{G}
Managorger Hydra
Creature - Hydra
Trample
Whenever a player casts a spell, put a +1/+1 counter on Managorger Hydra.
1 /
1
{3}{G}
Market Festival
Enchantment - Aura
Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional two mana in any combination of colors.
{1}{B}{B}
Murder
Instant
Destroy target creature.
--
Myriad Landscape
Land
Myriad Landscape enters the battlefield tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.
{4}{G}{G}
Nessian Wilds Ravager
Creature - Hydra
Tribute 6 (As this creature enters the battlefield, an opponent of your choice may put six +1/+1 counters on it.)
When Nessian Wilds Ravager enters the battlefield, if tribute wasn't paid, you may have Nessian Wilds Ravager fight another target creature. (Each deals damage equal to its power to the other.)
6 /
6
--
Opal Palace
Land
{T}: Add {C}.
{1}, {T}: Add one mana of any color in your commander's color identity. If you spend this mana to cast your commander, it enters the battlefield with a number of additional +1/+1 counters on it equal to the number of times it's been cast from the command zone this game.
--
Opulent Palace
Land
Opulent Palace enters the battlefield tapped.
{T}: Add {B}, {G}, or {U}.
{4}{G}{G}
Oran-Rief Hydra
Creature - Hydra
Trample
Landfall -- Whenever a land enters the battlefield under your control, put a +1/+1 counter on Oran-Rief Hydra. If that land is a Forest, put two +1/+1 counters on Oran-Rief Hydra instead.
5 /
5
--
Path of Ancestry
Land
Path of Ancestry enters the battlefield tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)
{X}{U}{B}
Psychic Drain
Sorcery
Target player mills X cards and you gain X life.
--
Radiant Fountain
Land
When Radiant Fountain enters the battlefield, you gain 2 life.
{T}: Add {C}.
{1}{G}
Rampant Growth
Sorcery
Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
{4}{U}
Reflections of Littjara
Enchantment
As Reflections of Littjara enters the battlefield, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)
--
Reliquary Tower
Land
You have no maximum hand size.
{T}: Add {C}.
{2}{G}{G}
Renata, Called to the Hunt
Legendary Enchantment Creature - Demigod
Renata's power is equal to your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)
Each other creature you control enters the battlefield with an additional +1/+1 counter on it.
* /
3
{G}{U}
Simic Ascendancy
Enchantment
{1}{G}{U}: Put a +1/+1 counter on target creature you control.
Whenever one or more +1/+1 counters are put on a creature you control, put that many growth counters on Simic Ascendancy.
At the beginning of your upkeep, if Simic Ascendancy has twenty or more growth counters on it, you win the game.
--
Simic Growth Chamber
Land
Simic Growth Chamber enters the battlefield tapped.
When Simic Growth Chamber enters the battlefield, return a land you control to its owner's hand.
{T}: Add {G}{U}.
{5}{G}
Slurrk, All-Ingesting
Legendary Creature - Ooze
Slurrk, All-Ingesting enters the battlefield with five +1/+1 counters on it.
Whenever Slurrk or another creature you control dies, if it had a +1/+1 counter on it, put a +1/+1 counter on each creature you control that has a +1/+1 counter on it.
Partner (You can have two commanders if both have partner.)
0 /
0
{1}
Sol Ring
Artifact
{T}: Add {C}{C}.
{1}{G}
Song of Freyalise
Enchantment - Saga
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II -- Until your next turn, creatures you control gain "{T}: Add one mana of any color."
III -- Put a +1/+1 counter on each creature you control. Those creatures gain vigilance, trample, and indestructible until end of turn.
{X}{G}{G}
Steelbane Hydra
Creature - Turtle Hydra
Steelbane Hydra enters the battlefield with X +1/+1 counters on it.
{2}{G}, Remove a +1/+1 counter from Steelbane Hydra: Destroy target artifact or enchantment.
0 /
0
{X}{G}{G}{G}
Stumpsquall Hydra
Creature - Hydra
When Stumpsquall Hydra enters the battlefield, distribute X +1/+1 counters among it and any number of commanders.
1 /
1
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Swamp
Basic Land - Swamp
({T}: Add {B}.)
--
Temple of the False God
Land
{T}: Add {C}{C}. Activate only if you control five or more lands.
--
Thornwood Falls
Land
Thornwood Falls enters the battlefield tapped.
When Thornwood Falls enters the battlefield, you gain 1 life.
{T}: Add {G} or {U}.
{X}{G}
Thrive
Sorcery
Put a +1/+1 counter on each of X target creatures.
{G/U}{G/U}{G/U}{G/U}
Thunderous Snapper
Creature - Turtle Hydra
Whenever you cast a spell with mana value 5 or greater, draw a card.
4 /
4
{4}{G}{G}
Ulvenwald Hydra
Creature - Hydra
Reach
Ulvenwald Hydra's power and toughness are each equal to the number of lands you control.
When Ulvenwald Hydra enters the battlefield, you may search your library for a land card, put it onto the battlefield tapped, then shuffle.
* /
*
{2}{G}
Unbound Flourishing
Enchantment
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.
{X}{G}{G}
Vastwood Hydra
Creature - Hydra
Vastwood Hydra enters the battlefield with X +1/+1 counters on it.
When Vastwood Hydra dies, you may distribute a number of +1/+1 counters equal to the number of +1/+1 counters on Vastwood Hydra among any number of creatures you control.
0 /
0
{5}{G}{G}
Verdant Sun's Avatar
Creature - Dinosaur Avatar
Whenever Verdant Sun's Avatar or another creature enters the battlefield under your control, you gain life equal to that creature's toughness.
5 /
5
{3}{G}{G}{G}
Vigor
Creature - Elemental Incarnation
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.
6 /
6
{X}{B}{G}{U}
Villainous Wealth
Sorcery
Target opponent exiles the top X cards of their library. You may cast any number of spells with mana value X or less from among them without paying their mana costs.
{X}{G}{G}
Voracious Hydra
Creature - Hydra
Trample
Voracious Hydra enters the battlefield with X +1/+1 counters on it.
When Voracious Hydra enters the battlefield, choose one --
• Double the number of +1/+1 counters on Voracious Hydra.
• Voracious Hydra fights target creature you don't control.
0 /
1
{5}{G}
Whiptongue Hydra
Creature - Lizard Hydra
Reach
When Whiptongue Hydra enters the battlefield, destroy all creatures with flying. Put a +1/+1 counter on Whiptongue Hydra for each creature destroyed this way.
4 /
4
{G}{G}{G}
Yorvo, Lord of Garenbrig
Legendary Creature - Giant Noble
Yorvo, Lord of Garenbrig enters the battlefield with four +1/+1 counters on it.
Whenever another green creature enters the battlefield under your control, put a +1/+1 counter on Yorvo. Then if that creature's power is greater than Yorvo's power, put another +1/+1 counter on Yorvo.
0 /
0
{1}{B}{G}{U}
Zaxara, the Exemplary
Legendary Creature - Nightmare Hydra
Deathtouch
{T}: Add two mana of any one color.
Whenever you cast a spell with {X} in its mana cost, create a 0/0 green Hydra creature token, then put X +1/+1 counters on it.