Rug of Smothering

Flying
Whenever a player casts a spell, they lose 1 life for each spell they've cast this turn.

Presence of the Master

Whenever a player casts an enchantment spell, counter it.

Paradise Plume

As Paradise Plume enters, choose a color.
Whenever a player casts a spell of the chosen color, you may gain 1 life.
{T}: Add one mana of the chosen color.

Jeweled Torque

As Jeweled Torque enters, choose a color.
Whenever a player casts a spell of the chosen color, you may pay {2}. If you do, you gain 2 life.

Roiling Vortex

At the beginning of each player's upkeep, Roiling Vortex deals 1 damage to them.
Whenever a player casts a spell, if no mana was spent to cast that spell, Roiling Vortex deals 5 damage to that player.
{R}: Your opponents can't gain life this turn.

Poisonbelly Ogre

Whenever another creature enters, its controller loses 1 life.

Togglodyte

Togglodyte enters turned on.
Whenever a player casts a spell, toggle Togglodyte's ON/OFF switch.
As long as Togglodyte is turned off, it can't attack or block, and prevent all damage it would deal.

Nether Void

Whenever a player casts a spell, counter it unless that player pays {3}.

Forgotten Ancient

Whenever a player casts a spell, you may put a +1/+1 counter on Forgotten Ancient.
At the beginning of your upkeep, you may move any number of +1/+1 counters from Forgotten Ancient onto other creatures.

Archfiend of Despair

Flying
Your opponents can't gain life.
At the beginning of each end step, each opponent loses life equal to the life that player lost this turn. (Damage causes loss of life.)

Thought Prison

Imprint — When Thought Prison enters, you may have target player reveal their hand. If you do, choose a nonland card from it and exile that card.
Whenever a player casts a spell that shares a color or mana value with the exiled card, Thought Prison deals 2 damage to that player.

Sunstrike Legionnaire

Sunstrike Legionnaire doesn't untap during your untap step.
Whenever another creature enters, untap Sunstrike Legionnaire.
{T}: Tap target creature with mana value 3 or less.

Hamletback Goliath

Whenever another creature enters, you may put X +1/+1 counters on Hamletback Goliath, where X is that creature's power.

Noosegraf Mob

Noosegraf Mob enters with five +1/+1 counters on it.
Whenever a player casts a spell, remove a +1/+1 counter from Noosegraf Mob. If you do, create a 2/2 black Zombie creature token.

Arcane Laboratory

Each player can't cast more than one spell each turn.

Unstable Shapeshifter

Whenever another creature enters, Unstable Shapeshifter becomes a copy of that creature, except it has this ability.

Arboria

Creatures can't attack a player unless that player cast a spell or put a nontoken permanent onto the battlefield during their last turn.

Antagonism

At the beginning of each player's end step, Antagonism deals 2 damage to that player unless one of their opponents was dealt damage this turn.

Pyrostatic Pillar

Whenever a player casts a spell with mana value 3 or less, Pyrostatic Pillar deals 2 damage to that player.

Archaeomancer's Map

When Archaeomancer's Map enters, search your library for up to two basic Plains cards, reveal them, put them into your hand, then shuffle.
Whenever a land an opponent controls enters, if that player controls more lands than you, you may put a land card from your hand onto the battlefield.

Spellshock

Whenever a player casts a spell, Spellshock deals 2 damage to that player.

Ancient Runes

At the beginning of each player's upkeep, Ancient Runes deals damage to that player equal to the number of artifacts they control.

Liesa, Shroud of Dusk

Rather than pay {2} for each previous time you've cast this spell from the command zone this game, pay 2 life that many times.
Flying, lifelink
Whenever a player casts a spell, they lose 2 life.

Ice Cave

Whenever a player casts a spell, any other player may pay that spell's mana cost. If a player does, counter the spell. (Mana cost includes color.)

Mana Echoes

Whenever a creature enters, you may add an amount of {C} equal to the number of creatures you control that share a creature type with it.

Auriok Champion

Protection from black and from red
Whenever another creature enters, you may gain 1 life.

Mirrorwing Dragon

Flying
Whenever a player casts an instant or sorcery spell that targets only Mirrorwing Dragon, that player copies that spell for each other creature they control that the spell could target. Each copy targets a different one of those creatures.

Void Mirror

Whenever a player casts a spell, if no colored mana was spent to cast it, counter that spell.

Archon of Valor's Reach

Flying, vigilance, trample
As Archon of Valor's Reach enters, choose artifact, enchantment, instant, sorcery, or planeswalker.
Players can't cast spells of the chosen type.

Ink-Treader Nephilim

Whenever a player casts an instant or sorcery spell, if that spell targets only Ink-Treader Nephilim, copy the spell for each other creature that spell could target. Each copy targets a different one of those creatures.

Eidolon of the Great Revel

Whenever a player casts a spell with mana value 3 or less, Eidolon of the Great Revel deals 2 damage to that player.

Water Gun Balloon Game

As Water Gun Balloon Game enters, each player puts a pop! counter on "0."
Whenever a player casts a spell, move that player's pop! counter up one.
Whenever a player's pop! counter hits "5," that player creates a 5/5 pink Giant Teddy Bear creature token and resets all pop! counters to "0."

Reparations

Whenever an opponent casts a spell that targets you or a creature you control, you may draw a card.

Pure Reflection

Whenever a player casts a creature spell, destroy all Reflections. Then that player creates an X/X white Reflection creature token, where X is the mana value of that spell.

Essence Warden

Whenever another creature enters, you gain 1 life.

Alms Collector

Flash
If an opponent would draw two or more cards, instead you and that player each draw a card.

Aether Flash

Whenever a creature enters, Aether Flash deals 2 damage to it.

Rod of Absorption

Whenever a player casts an instant or sorcery spell, exile it instead of putting it into a graveyard as it resolves.
{X}, {T}, Sacrifice Rod of Absorption: You may cast any number of spells from among cards exiled with Rod of Absorption with total mana value X or less without paying their mana costs.

Vazi, Keen Negotiator

Haste
{T}: Target opponent creates X Treasure tokens, where X is the number of Treasure tokens you created this turn.
Whenever an opponent casts a spell or activates an ability, if mana from a Treasure was spent to cast it or activate it, put a +1/+1 counter on target creature, then draw a card.

Agitator Ant

At the beginning of your end step, each player may put two +1/+1 counters on a creature they control. Goad each creature that had counters put on it this way. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Bonus Round

Until end of turn, whenever a player casts an instant or sorcery spell, that player copies it and may choose new targets for the copy.

Lone Wolf of the Natterknolls

Whenever an opponent casts a spell during your turn, draw two cards.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform Lone Wolf of the Natterknolls.

Hermit of the Natterknolls

Whenever an opponent casts a spell during your turn, draw a card.
At the beginning of each upkeep, if no spells were cast last turn, transform Hermit of the Natterknolls.

Hermit of the Natterknolls // Lone Wolf of the Natterknolls

Common Courtesy

Whenever a player casts a spell without asking your permission while casting it, counter that spell.
When a player asks you permission to cast a spell and you refuse, counter that spell and sacrifice Common Courtesy.

Eye of the Storm

Whenever a player casts an instant or sorcery card, exile it. Then that player copies each instant or sorcery card exiled with Eye of the Storm. For each copy, the player may cast the copy without paying its mana cost.

Aether Sting

Whenever an opponent casts a creature spell, Aether Sting deals 1 damage to that player.

Emcee

Whenever another creature enters, you may stand up and say in a deep, booming voice, "Presenting . . . " and that creature's name. If you do, put a +1/+1 counter on that creature.

Rampaging Ferocidon

Menace
Players can't gain life.
Whenever another creature enters, Rampaging Ferocidon deals 1 damage to that creature's controller.

B-I-N-G-O

Trample
Whenever a player casts a spell, put a chip counter on its mana value.
B-I-N-G-O gets +9/+9 for each set of three numbers in a row with chip counters on them.

Spreading Plague

Whenever a creature enters, destroy all other creatures that share a color with it. They can't be regenerated.

Possibility Storm

Whenever a player casts a spell from their hand, that player exiles it, then exiles cards from the top of their library until they exile a card that shares a card type with it. That player may cast that card without paying its mana cost. Then they put all cards exiled with Possibility Storm on the bottom of their library in a random order.

Ash Zealot

First strike, haste
Whenever a player casts a spell from a graveyard, Ash Zealot deals 3 damage to that player.

Staff of the Letter Magus

As Staff of the Letter Magus enters, choose a consonant other than N, R, S, or T.
Whenever a player casts a spell, you gain 1 life for each time the chosen letter appears in that spell's name.

Mirror of Life Trapping

Whenever a creature enters, if it was cast, exile it, then return all other permanent cards exiled with Mirror of Life Trapping to the battlefield under their owners' control.

Hive Mind

Whenever a player casts an instant or sorcery spell, each other player copies that spell. Each of those players may choose new targets for their copy.

Soul Warden

Selvala, Heart of the Wilds

Whenever another creature enters, 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.

Archfiend of Depravity

Flying
At the beginning of each opponent's end step, that player chooses up to two creatures they control, then sacrifices the rest.

Angel's Feather

Whenever a player casts a white spell, you may gain 1 life.

Angel's Trumpet

All creatures have vigilance.
At the beginning of each player's end step, tap all untapped creatures that player controls that didn't attack this turn. Angel's Trumpet deals damage to the player equal to the number of creatures tapped this way.

Apothecary Initiate

Whenever a player casts a white spell, you may pay {1}. If you do, you gain 1 life.

All Hallow's Eve

Exile All Hallow's Eve with two scream counters on it.
At the beginning of your upkeep, if All Hallow's Eve is exiled with a scream counter on it, remove a scream counter from it. If there are no more scream counters on it, put it into your graveyard and each player returns all creature cards from their graveyard to the battlefield.

False Cure

Until end of turn, whenever a player gains life, that player loses 2 life for each 1 life they gained.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Geometric Nexus

Whenever a player casts an instant or sorcery spell, put a number of charge counters on Geometric Nexus equal to that spell's mana value.
{6}, {T}, Remove all charge counters from Geometric Nexus: Create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it, where X is the number of charge counters removed this way.

Tangleroot

Whenever a player casts a creature spell, that player adds {G}.

In the Eye of Chaos

Whenever a player casts an instant spell, counter it unless that player pays {X}, where X is its mana value.

Managorger Hydra

Trample
Whenever a player casts a spell, put a +1/+1 counter on Managorger Hydra.

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Curse of Wizardry

As Curse of Wizardry enters, choose a color.
Whenever a player casts a spell of the chosen color, that player loses 1 life.

Midnight Guard

Whenever another creature enters, untap Midnight Guard.

Swindler's Scheme

Whenever an opponent casts a spell from their hand, you may reveal the top card of your library. If it shares a card type with that spell, counter that spell and that opponent may cast the revealed card without paying its mana cost.

Acidic Soil

Acidic Soil deals damage to each player equal to the number of lands they control.

Chalice of the Void

Chalice of the Void enters with X charge counters on it.
Whenever a player casts a spell with mana value equal to the number of charge counters on Chalice of the Void, counter that spell.

Aether Barrier

Whenever a player casts a creature spell, that player sacrifices a permanent of their choice unless they pay {1}.

Voice of Resurgence

Whenever an opponent casts a spell during your turn and when Voice of Resurgence dies, create a green and white Elemental creature token with "This creature's power and toughness are each equal to the number of creatures you control."

Planar Chaos

At the beginning of your upkeep, flip a coin. If you lose the flip, sacrifice Planar Chaos.
Whenever a player casts a spell, that player flips a coin. If they lose the flip, counter that spell.