Hullbreacher

Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

The Countdown Is at One

Players play a Magic subgame, starting at 1 life and using their libraries as their decks. For the rest of the main game, if a source would deal damage to a player who didn't win the subgame, it deals double that damage to that player instead.

Cyclonic Rift

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.")

Parallax Tide

Fading 5 (This enchantment enters with five fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from Parallax Tide: Exile target land.
When Parallax Tide leaves the battlefield, each player returns to the battlefield all cards they own exiled with Parallax Tide.

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.

Glorious End

End the turn. (Exile all spells and abilities from the stack, including this card. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)
At the beginning of your next end step, you lose the game.

Perplexing Chimera

Whenever an opponent casts a spell, you may exchange control of Perplexing Chimera and that spell. If you do, you may choose new targets for the spell. (If the spell becomes a permanent, you control that permanent.)

Tangle Wire

Fading 4 (This artifact enters with four fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
At the beginning of each player's upkeep, that player taps an untapped artifact, creature, or land they control for each fade counter on Tangle Wire.

Lethal Vapors

Whenever a creature enters, destroy it.
{0}: Destroy Lethal Vapors. You skip your next turn. Any player may activate this ability.

Torpor Orb

Creatures entering don't cause abilities to trigger.

Notion Thief

Flash
If an opponent would draw a card except the first one they draw in each of their draw steps, instead that player skips that draw and you draw a card.

Rising Waters

Lands don't untap during their controllers' untap steps.
At the beginning of each player's upkeep, that player untaps a land they control.

Eon Hub

Mindslaver

{4}, {T}, Sacrifice Mindslaver: You control target player during that player's next turn. (You see all cards that player could see and make all decisions for the player.)

Sundial of the Infinite

{1}, {T}: End the turn. Activate only during your turn. (Exile all spells and abilities from the stack. Discard down to your maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Frozen Aether

Artifacts, creatures, and lands your opponents control enter tapped.

Mana Breach

Whenever a player casts a spell, that player returns a land they control to its owner's hand.

Paradigm Shift

Exile all cards from your library. Then shuffle your graveyard into your library.

Fatespinner

At the beginning of each opponent's upkeep, that player chooses draw step, main phase, or combat phase. The player skips each instance of the chosen step or phase this turn.

Possessed Portal

If a player would draw a card, that player skips that draw instead.
At the beginning of each end step, each player sacrifices a permanent of their choice unless they discard a card.

Discontinuity

During your turn, this spell costs {2}{U}{U} less to cast.
End the turn. (Exile all spells and abilities from the stack, including this card. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Obeka, Brute Chronologist

{T}: The player whose turn it is may end the turn. (Exile all spells and abilities from the stack. The player whose turn it is discards down to their maximum hand size. Damage wears off, and "this turn" and "until end of turn" effects end.)

Turnabout

Choose artifact, creature, or land. Tap all untapped permanents of the chosen type target player controls, or untap all tapped permanents of that type that player controls.

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.)

Sands of Time

Each player skips their untap step.
At the beginning of each player's upkeep, that player simultaneously untaps each tapped artifact, creature, and land they control and taps each untapped artifact, creature, and land they control.

Arcane Laboratory

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

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.

Magosi, the Waterveil

Magosi, the Waterveil enters tapped.
{T}: Add {U}.
{U}, {T}: Put an eon counter on Magosi, the Waterveil. Skip your next turn.
{T}, Remove an eon counter from Magosi, the Waterveil and return it to its owner's hand: Take an extra turn after this one.

Stranglehold

Your opponents can't search libraries.
If an opponent would begin an extra turn, that player skips that turn instead.

Brine Elemental

Morph {5}{U}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When Brine Elemental is turned face up, each opponent skips their next untap step.

Tempt with Reflections

Tempting offer — Choose target creature you control. Create a token that's a copy of that creature. Each opponent may create a token that's a copy of that creature. For each opponent who does, create a token that's a copy of that creature.

Insurrection

Untap all creatures and gain control of them until end of turn. They gain haste until end of turn.

Plagiarize

Until end of turn, if target player would draw a card, instead that player skips that draw and you draw a card.

Dawn of the Dead

At the beginning of your upkeep, you lose 1 life.
At the beginning of your upkeep, you may return target creature card from your graveyard to the battlefield. That creature gains haste until end of turn. Exile it at the beginning of the next end step.

Mimic Vat

Imprint — Whenever a nontoken creature dies, you may exile that card. If you do, return each other card exiled with Mimic Vat to its owner's graveyard.
{3}, {T}: Create a token that's a copy of a card exiled with Mimic Vat. It gains haste. Exile it at the beginning of the next end step.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Vedalken Orrery

You may cast spells as though they had flash.

Stasis

Players skip their untap steps.
At the beginning of your upkeep, sacrifice Stasis unless you pay {U}.

Telepathy

Your opponents play with their hands revealed.

Tribute Mage

When Tribute Mage enters, you may search your library for an artifact card with mana value 2, reveal that card, put it into your hand, then shuffle.

Hellkite Courser

Flying
When Hellkite Courser enters, you may put a commander you own from the command zone onto the battlefield. It gains haste. Return it to the command zone at the beginning of the next end step.

Glacial Chasm

Cumulative upkeep—Pay 2 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When Glacial Chasm enters, sacrifice a land.
Creatures you control can't attack.
Prevent all damage that would be dealt to you.

Enter the Dungeon

Players play a Magic subgame under the table, starting at 5 life and using their libraries as their decks. The winner searches their library for two cards, puts those cards into their hand, then shuffles.

Mirrormade

You may have Mirrormade enter as a copy of any artifact or enchantment on the battlefield.