Illicit Auction

Each player may bid life for control of target creature. You start the bidding with a bid of 0. In turn order, each player may top the high bid. The bidding ends if the high bid stands. The high bidder loses life equal to the high bid and gains control of the creature. (This effect lasts indefinitely.)

Knowledge Pool

Imprint — When Knowledge Pool enters the battlefield, each player exiles the top three cards of their library.
Whenever a player casts a spell from their hand, that player exiles it. If the player does, they may cast a spell from among other cards exiled with Knowledge Pool without paying its mana cost.

Inferno

Inferno deals 6 damage to each creature and each player.

Natural Balance

Each player who controls six or more lands chooses five lands they control and sacrifices the rest. Each player who controls four or fewer lands may search their library for up to X basic land cards and put them onto the battlefield, where X is five minus the number of lands they control. Then each player who searched their library this way shuffles.

Pyrrhic Revival

Each player returns each creature card from their graveyard to the battlefield with an additional -1/-1 counter on it.

Nature's Revolt

All lands are 2/2 creatures that are still lands.

Font of Mythos

At the beginning of each player's draw step, that player draws two additional cards.

Crack the Earth

Furnace of Rath

If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Maralen of the Mornsong

Players can't draw cards.
At the beginning of each player's draw step, that player loses 3 life, searches their library for a card, puts it into their hand, then shuffles.

Wild Evocation

At the beginning of each player's upkeep, that player reveals a card at random from their hand. If it's a land card, the player puts it onto the battlefield. Otherwise, the player casts it without paying its mana cost if able.

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.

Day of Judgment

Kamahl's Summons

Each player may reveal any number of creature cards from their hand. Then each player creates a 2/2 green Bear creature token for each card they revealed this way.

Arcane Melee

Instant and sorcery spells cost {2} less to cast.

Dueling Grounds

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

Gate to the Aether

At the beginning of each player's upkeep, that player reveals the top card of their library. If it's an artifact, creature, enchantment, or land card, the player may put it onto the battlefield.

Ley Line

At the beginning of each player's upkeep, that player may put a +1/+1 counter on target creature of their choice.

Crumbling Sanctuary

If damage would be dealt to a player, that player exiles that many cards from the top of their library instead.

Impulsive Maneuvers

Whenever a creature attacks, flip a coin. If you win the flip, the next time that creature would deal combat damage this turn, it deals double that damage instead. If you lose the flip, the next time that creature would deal combat damage this turn, prevent that damage.

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.

Strategy, Schmategy

Roll a six-sided die. Strategy, Schmategy has the indicated effect.
1 — Do nothing.
2 — Destroy all artifacts.
3 — Destroy all lands.
4 — Strategy, Schmategy deals 3 damage to each creature and each player.
5 — Each player discards their hand and draws seven cards.
6 — Repeat this process two more times.

Evacuation

Return all creatures to their owners' hands.

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.

Sway of the Stars

Each player shuffles their hand, graveyard, and all permanents they own into their library, then draws seven cards. Each player's life total becomes 7.

Mass Hysteria

Bludgeon Brawl

Each noncreature, non-Equipment artifact is an Equipment with equip {X} and "Equipped creature gets +X/+0," where X is that artifact's mana value.

Mnemonic Nexus

Each player shuffles their graveyard into their library.

Rites of Flourishing

At the beginning of each player's draw step, that player draws an additional card.
Each player may play an additional land on each of their turns.

Unifying Theory

Whenever a player casts a spell, that player may pay {2}. If the player does, they draw a card.

Truce

Each player may draw up to two cards. For each card less than two a player draws this way, that player gains 2 life.

Biorhythm

Each player's life total becomes the number of creatures they control.

Earnest Fellowship

Each creature has protection from its colors.

Flame Rift

Flame Rift deals 4 damage to each player.

Heat Stroke

At end of combat, destroy each creature that blocked or was blocked this turn.

Vision Skeins

Spiteful Visions

At the beginning of each player's draw step, that player draws an additional card.
Whenever a player draws a card, Spiteful Visions deals 1 damage to that player.

Limited Resources

When Limited Resources enters the battlefield, each player chooses five lands they control and sacrifices the rest.
Players can't play lands as long as ten or more lands are on the battlefield.

Clear the Land

Each player reveals the top five cards of their library, puts all land cards revealed this way onto the battlefield tapped, and exiles the rest.

Pandemonium

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

Hypergenesis

Suspend 3—{1}{G}{G}
Starting with you, each player may put an artifact, creature, enchantment, or land card from their hand onto the battlefield. Repeat this process until no one puts a card onto the battlefield.

Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

Grand Melee

All creatures attack each combat if able.
All creatures block each combat if able.

Coat of Arms

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

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.

Upwelling

Players don't lose unspent mana as steps and phases end.

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.

Saproling Cluster

{1}, Discard a card: Create a 1/1 green Saproling creature token. Any player may activate this ability.

Plague of Vermin

Starting with you, each player may pay any amount of life. Repeat this process until no one pays life. Each player creates a 1/1 black Rat creature token for each 1 life they paid this way.

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.

Delirium Skeins

Ghirapur Orrery

Each player may play an additional land on each of their turns.
At the beginning of each player's upkeep, if that player has no cards in hand, that player draws three cards.

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.