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}{G}
Animist's Awakening
Sorcery
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.
{2}
Arcane Signet
Artifact
{T}: Add one mana of any color in your commander's color identity.
{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.
--
Blighted Woodland
Land
{T}: Add {C}.
{3}{G}, {T}, Sacrifice Blighted Woodland: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
{X}{U}{U}{U}
Blue Sun's Zenith
Instant
Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.
--
Bojuka Bog
Land
Bojuka Bog enters the battlefield tapped.
When Bojuka Bog enters the battlefield, exile target player's graveyard.
{T}: Add {B}.
{2}{G}
Branching Evolution
Enchantment
If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on that creature instead.
{X}{G}
Capricopian
Creature - Goat Hydra
Capricopian enters the battlefield with X +1/+1 counters on it.
{2}: Put a +1/+1 counter on Capricopian, then you may reselect which player Capricopian is attacking. Only the player Capricopian is attacking may activate this ability and only during the declare attackers step. (It can't attack its controller.)
0 /
0
--
Castle Garenbrig
Land
Castle Garenbrig enters the battlefield tapped unless you control a Forest.
{T}: Add {G}.
{2}{G}{G}, {T}: Add six {G}. Spend this mana only to cast creature spells or activate abilities of creatures.
{3}
Chromatic Lantern
Artifact
Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.
{X}{U}
Clash of Wills
Instant
Counter target spell unless its controller pays {X}.
--
Clearwater Pathway
Land
{T}: Add {U}.
--
Murkwater Pathway
Land
{T}: Add {B}.
--
Command Tower
Land
{T}: Add one mana of any color in your commander's color identity.
{X}{U}
Condescend
Instant
Counter target spell unless its controller pays {X}. Scry 2. (Look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)
{2}{B}{G}
Corpsejack Menace
Creature - Fungus
If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on it instead.
4 /
4
{2}{G}
Cultivate
Sorcery
Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.
{1}{U}
Cyclonic Rift
Instant
Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")
{3}{B}
Deadly Rollick
Instant
If you control a commander, you may cast this spell without paying its mana cost.
Exile target creature.
{1}{B}{B}{G}
Deathsprout
Instant
Destroy target creature. Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{1}{B}
Demonic Tutor
Sorcery
Search your library for a card, put that card into your hand, then shuffle.
{2}
Dimir Signet
Artifact
{1}, {T}: Add {U}{B}.
{X}{1}{U}{U}
Dominate
Instant
Gain control of target creature with mana value X or less.
{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.
{1}{G}{G}
Eternal Witness
Creature - Human Shaman
When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.
2 /
1
--
Evolving Wilds
Land
{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{3}{G}
Explosive Vegetation
Sorcery
Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
{X}{B}{B}
Exsanguinate
Sorcery
Each opponent loses X life. You gain life equal to the life lost this way.
{2}{G}
Fertilid
Creature - Elemental
Fertilid enters the battlefield with two +1/+1 counters on it.
{1}{G}, Remove a +1/+1 counter from Fertilid: Target player searches their library for a basic land card, puts it onto the battlefield tapped, then shuffles.
0 /
0
--
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}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
{2}{U}
Freed from the Real
Enchantment - Aura
Enchant creature
{U}: Tap enchanted creature.
{U}: Untap enchanted creature.
{X}{U}{U}{U}
Gadwick, the Wizened
Legendary Creature - Human Wizard
When Gadwick, the Wizened enters the battlefield, draw X cards.
Whenever you cast a blue spell, tap target nonland permanent an opponent controls.
3 /
3
{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.
{5}
Gilded Lotus
Artifact
{T}: Add three mana of any one color.
{2}
Golgari Signet
Artifact
{1}, {T}: Add {B}{G}.
--
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}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
{3}{G}{G}
Kalonian Hydra
Creature - Hydra
Trample
Kalonian Hydra enters the battlefield with four +1/+1 counters on it.
Whenever Kalonian Hydra attacks, double the number of +1/+1 counters on each creature you control.
0 /
0
--
Karn's Bastion
Land
{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
{2}{G}
Kodama's Reach
Sorcery - Arcane
Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.
{2}{G}
Krosan Grip
Instant
Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Destroy target artifact or enchantment.
{3}{G}{U}
Kruphix, God of Horizons
Legendary Enchantment Creature - God
Indestructible
As long as your devotion to green and blue is less than seven, Kruphix isn't a creature.
You have no maximum hand size.
If you would lose unspent mana, that mana becomes colorless instead.
4 /
7
{2}{U}{U}
Leyline of Anticipation
Enchantment
If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash.
{X}{G}{G}{G}
Lifeblood Hydra
Creature - Hydra
Trample
Lifeblood Hydra enters the battlefield with X +1/+1 counters on it.
When Lifeblood Hydra dies, you gain life and draw cards equal to its power.
0 /
0
{2}
Lightning Greaves
Artifact - Equipment
Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}
{X}{U}{U}
Logic Knot
Instant
Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Counter target spell unless its controller pays {X}.
{X}{U}{U}
Mind Spring
Sorcery
Draw X cards.
--
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.
{U}
Mystical Tutor
Instant
Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.
{X}{G}{U}
Nimbus Swimmer
Creature - Leviathan
Flying
Nimbus Swimmer enters the battlefield with X +1/+1 counters on it.
0 /
0
{3}{G}
Nylea, God of the Hunt
Legendary Enchantment Creature - God
Indestructible
As long as your devotion to green is less than five, Nylea isn't a creature. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)
Other creatures you control have trample.
{3}{G}: Target creature gets +2/+2 until end of turn.
6 /
6
--
Opulent Palace
Land
Opulent Palace enters the battlefield tapped.
{T}: Add {B}, {G}, or {U}.
{1}{U}{U}
Pemmin's Aura
Enchantment - Aura
Enchant creature
{U}: Untap enchanted creature.
{U}: Enchanted creature gains flying until end of turn.
{U}: Enchanted creature gains shroud until end of turn. (It can't be the target of spells or abilities.)
{1}: Enchanted creature gets +1/-1 or -1/+1 until end of turn.
{X}{G}{G}
Primordial Hydra
Creature - Hydra
Primordial Hydra enters the battlefield with X +1/+1 counters on it.
At the beginning of your upkeep, double the number of +1/+1 counters on Primordial Hydra.
Primordial Hydra has trample as long as it has ten or more +1/+1 counters on it.
0 /
0
{X}{G}
Protean Hydra
Creature - Hydra
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.
0 /
0
{X}{U}{U}
Pull from Tomorrow
Instant
Draw X cards, then discard a card.
{1}{B}{G}
Putrefy
Instant
Destroy target artifact or creature. It can't be regenerated.
{2}{G}
Reclamation Sage
Creature - Elf Shaman
When Reclamation Sage enters the battlefield, you may destroy target artifact or enchantment.
2 /
1
{2}{U}
Rhystic Study
Enchantment
Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.
--
Rogue's Passage
Land
{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.
{1}{G}
Sakura-Tribe Elder
Creature - Snake Shaman
Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
1 /
1
{3}{G}{G}
Seedborn Muse
Creature - Spirit
Untap all permanents you control during each other player's untap step.
2 /
4
{1}{G}{G}
Selvala, Heart of the Wilds
Legendary Creature - Elf Scout
Whenever another creature enters the battlefield, its controller may draw a card if its power is greater than each other creature's power.
{G}, {T}: Add X mana in any combination of colors, where X is the greatest power among creatures you control.
2 /
3
{2}
Simic Signet
Artifact
{1}, {T}: Add {G}{U}.
{1}
Sol Ring
Artifact
{T}: Add {C}{C}.
{X}{U}
Spell Burst
Instant
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.)
Counter target spell with mana value X.
{X}{2}{U}
Stroke of Genius
Instant
Target player draws X cards.
--
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}.)
{2}
Swiftfoot Boots
Artifact - Equipment
Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}
{X}{U}
Syncopate
Instant
Counter target spell unless its controller pays {X}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.
--
Temple of the False God
Land
{T}: Add {C}{C}. Activate only if you control five or more lands.
--
Terramorphic Expanse
Land
{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{X}{U}{U}
Thassa's Intervention
Instant
Choose one --
• Look at the top X cards of your library. Put up to two of them into your hand and the rest on the bottom of your library in a random order.
• Counter target spell unless its controller pays twice {X}.
{1}
The Ozolith
Legendary Artifact
Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.
At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.
{4}
Thran Dynamo
Artifact
{T}: Add {C}{C}{C}.
{X}{B}{B}
Torment of Hailfire
Sorcery
Repeat the following process X times. Each opponent loses 3 life unless that player sacrifices a nonland permanent or discards a card.
{2}{B}
Toxic Deluge
Sorcery
As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.
{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.
{1}{G}{U}
Vorel of the Hull Clade
Legendary Creature - Human Merfolk
{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.
1 /
4
{X}{X}
Walking Ballista
Artifact Creature - Construct
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.
0 /
0
{X}{G}
Wildwood Scourge
Creature - Hydra
Wildwood Scourge enters the battlefield with X +1/+1 counters on it.
Whenever one or more +1/+1 counters are put on another non-Hydra creature you control, put a +1/+1 counter on Wildwood Scourge.
0 /
0
{G}
Worldly Tutor
Instant
Search your library for a creature card, reveal it, then shuffle and put the card on top.
--
Zagoth Triome
Land - Swamp Forest Island
({T}: Add {B}, {G}, or {U}.)
Zagoth Triome enters the battlefield tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)
{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.
2 /
3
{5}{G}{G}
Zendikar Resurgent
Enchantment
Whenever you tap a land for mana, add one mana of any type that land produced. (The types of mana are white, blue, black, red, green, and colorless.)