Reverberate

Copy target instant or sorcery spell. You may choose new targets for the copy.

Myr Battlesphere

When Myr Battlesphere enters, create four 1/1 colorless Myr artifact creature tokens.
Whenever Myr Battlesphere attacks, you may tap X untapped Myr you control. If you do, Myr Battlesphere gets +X/+0 until end of turn and deals X damage to the player or planeswalker it's attacking.

Harsh Mentor

Whenever an opponent activates an ability of an artifact, creature, or land on the battlefield, if it isn't a mana ability, Harsh Mentor deals 2 damage to that player.

Goblin Matron

When Goblin Matron enters, you may search your library for a Goblin card, reveal that card, put it into your hand, then shuffle.

Mana Clash

You and target opponent each flip a coin. Mana Clash deals 1 damage to each player whose coin comes up tails. Repeat this process until both players' coins come up heads on the same flip.

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.

Fork

Copy target instant or sorcery spell, except that the copy is red. You may choose new targets for the copy.

Twist Allegiance

You and target opponent each gain control of all creatures the other controls until end of turn. Untap those creatures. Those creatures gain haste until end of turn.

Norin the Wary

When a player casts a spell or a creature attacks, exile Norin the Wary. Return it to the battlefield under its owner's control at the beginning of the next end step.

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Scrambleverse

For each nonland permanent, choose a player at random. Then each player gains control of each permanent for which they were chosen. Untap those permanents.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Krenko, Mob Boss

{T}: Create X 1/1 red Goblin creature tokens, where X is the number of Goblins you control.

Burnished Hart

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")

Wild Ricochet

You may choose new targets for target instant or sorcery spell. Then copy that spell. You may choose new targets for the copy.

Siege-Gang Commander

When Siege-Gang Commander enters, create three 1/1 red Goblin creature tokens.
{1}{R}, Sacrifice a Goblin: Siege-Gang Commander deals 2 damage to any target.

Sol Ring

Dreamstone Hedron

{T}: Add {C}{C}{C}.
{3}, {T}, Sacrifice Dreamstone Hedron: Draw three cards.

Goblin Game

Each player hides at least one item, then all players reveal them simultaneously. Each player loses life equal to the number of items they revealed. The player who revealed the fewest items then loses half their life, rounded up. If two or more players are tied for fewest, each loses half their life, rounded up.

Hedron Archive

{T}: Add {C}{C}.
{2}, {T}, Sacrifice Hedron Archive: Draw two cards.

Krark's Thumb

If you would flip a coin, instead flip two coins and ignore one.

Zealous Conscripts

Haste
When Zealous Conscripts enters, gain control of target permanent until end of turn. Untap that permanent. It gains haste until end of turn.

Silent Arbiter

No more than one creature can attack each combat.
No more than one creature can block each combat.

Hamletback Goliath

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

Whims of the Fates

Starting with you, each player separates all permanents they control into three piles. Then each player chooses one of their piles at random and sacrifices those permanents. (Piles can be empty.)

Fiery Gambit

Flip a coin until you lose a flip or choose to stop flipping. If you lose a flip, Fiery Gambit has no effect. If you win one or more flips, Fiery Gambit deals 3 damage to target creature. If you win two or more flips, Fiery Gambit deals 6 damage to each opponent. If you win three or more flips, draw nine cards and untap all lands you control.

Grip of Chaos

Whenever a spell or ability is put onto the stack, if it has a single target, reselect its target at random. (Select from among all legal targets.)

Beetleback Chief

When Beetleback Chief enters, create two 1/1 red Goblin creature tokens.

Disrupt Decorum

Goad all creatures you don't control. (Until your next turn, those creatures attack each combat if able and attack a player other than you if able.)

Tibalt, the Fiend-Blooded

+1: Draw a card, then discard a card at random.
−4: Tibalt, the Fiend-Blooded deals damage equal to the number of cards in target player's hand to that player.
−6: Gain control of all creatures until end of turn. Untap them. They gain haste until end of turn.

Goblin Welder

{T}: Choose target artifact a player controls and target artifact card in that player's graveyard. If both targets are still legal as this ability resolves, that player simultaneously sacrifices the artifact and returns the artifact card to the battlefield.

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Reforge the Soul

Each player discards their hand, then draws seven cards.
Miracle {1}{R} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Mountain

Solemn Simulacrum

When Solemn Simulacrum enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Teferi's Puzzle Box

At the beginning of each player's draw step, that player puts the cards in their hand on the bottom of their library in any order, then draws that many cards.

Squee, Goblin Nabob

At the beginning of your upkeep, you may return Squee, Goblin Nabob from your graveyard to your hand.

Reiterate

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.)
Copy target instant or sorcery spell. You may choose new targets for the copy.

Warp World

Each player shuffles all permanents they own into their library, then reveals that many cards from the top of their library. Each player puts all artifact, creature, and land cards revealed this way onto the battlefield, then does the same for enchantment cards, then puts all cards revealed this way that weren't put onto the battlefield on the bottom of their library.

Word of Seizing

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Untap target permanent and gain control of it until end of turn. It gains haste until end of turn.

Kiki-Jiki, Mirror Breaker

Haste
{T}: Create a token that's a copy of target nonlegendary creature you control, except it has haste. Sacrifice it at the beginning of the next end step.

Magus of the Moon

Game of Chaos

Flip a coin. If you win the flip, you gain 1 life and target opponent loses 1 life, and you decide whether to flip again. If you lose the flip, you lose 1 life and that opponent gains 1 life, and that player decides whether to flip again. Double the life stakes with each flip.

Confusion in the Ranks

Whenever an artifact, creature, or enchantment enters, its controller chooses target permanent another player controls that shares a card type with it. Exchange control of those permanents.

Kher Keep

{T}: Add {C}.
{1}{R}, {T}: Create a 0/1 red Kobold creature token named Kobolds of Kher Keep.

Genesis Chamber

Whenever a nontoken creature enters, if Genesis Chamber is untapped, that creature's controller creates a 1/1 colorless Myr artifact creature token.

Caged Sun

As Caged Sun enters, 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.

Goblin Assassin

Whenever Goblin Assassin or another Goblin enters, each player flips a coin. Each player whose coin comes up tails sacrifices a creature.

Cloudstone Curio

Whenever a nonartifact permanent you control enters, you may return another permanent you control that shares a permanent type with it to its owner's hand.

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.

Squee, the Immortal

You may cast Squee, the Immortal from your graveyard or from exile.

Radiate

Choose target instant or sorcery spell that targets only a single permanent or player. Copy that spell for each other permanent or player the spell could target. Each copy targets a different one of those permanents and players.

Sensei's Divining Top

{1}: Look at the top three cards of your library, then put them back in any order.
{T}: Draw a card, then put Sensei's Divining Top on top of its owner's library.

Mirage Mirror

{2}: Mirage Mirror becomes a copy of target artifact, creature, enchantment, or land until end of turn.

Kari Zev, Skyship Raider

First strike, menace
Whenever Kari Zev, Skyship Raider attacks, create Ragavan, a legendary 2/1 red Monkey creature token. Ragavan enters tapped and attacking. Exile that token at end of combat.

Ogre Battledriver

Whenever another creature you control enters, that creature gets +2/+0 and gains haste until end of turn. (It can attack and {T} this turn.)

Gamble

Search your library for a card, put that card into your hand, discard a card at random, then shuffle.

Pandemonium

Whenever a creature enters, that creature's controller may have it deal damage equal to its power to any target of their choice.

Wheel of Fate

Suspend 4—{1}{R} (Rather than cast this card from your hand, pay {1}{R} and exile it with four time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Each player discards their hand, then draws seven cards.

Conjurer's Closet

At the beginning of your end step, you may exile target creature you control, then return that card to the battlefield under your control.