One with the Multiverse

You may look at the top card of your library any time.
You may play lands and cast spells from the top of your library.
Once during each of your turns, you may cast a spell from your hand or the top of your library without paying its mana cost.

Psychic Possession

Enchant opponent
Skip your draw step.
Whenever enchanted opponent draws a card, you may draw a card.

Clever Impersonator

You may have Clever Impersonator enter the battlefield as a copy of any nonland permanent on the battlefield.

Maddening Cacophony

Kicker {3}{U}
Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

Agent of Treachery

When Agent of Treachery enters the battlefield, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Ghouls' Night Out

For each player, choose a creature card in that player's graveyard. Put those cards onto the battlefield under your control. They're black Zombies in addition to their other colors and types and they gain decayed. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Vesuvan Duplimancy

Whenever you cast a spell that targets only a single artifact or creature you control, create a token that's a copy of that artifact or creature, except it's not legendary.

Memory Plunder

You may cast target instant or sorcery card from an opponent's graveyard without paying its mana cost.

Baleful Strix

Flying, deathtouch
When Baleful Strix enters the battlefield, draw a card.

Mocking Doppelganger

Flash
You may have Mocking Doppelganger enter the battlefield as a copy of a creature an opponent controls, except it has "Other creatures with the same name as this creature are goaded." (They attack each combat if able and attack a player other than you if able.)

Massacre Wurm

When Massacre Wurm enters the battlefield, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Displace

Exile up to two target creatures you control, then return those cards to the battlefield under their owner's control.

Mind's Dilation

Whenever an opponent casts their first spell each turn, that player exiles the top card of their library. If it's a nonland card, you may cast it without paying its mana cost.

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.

Diluvian Primordial

Flying
When Diluvian Primordial enters the battlefield, for each opponent, you may cast up to one target instant or sorcery card from that player's graveyard without paying its mana cost. If a spell cast this way would be put into a graveyard, exile it instead.

Clone

You may have Clone enter the battlefield as a copy of any creature on the battlefield.

Drowned Catacomb

Drowned Catacomb enters the battlefield tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

Irenicus's Vile Duplication

Create a token that's a copy of target creature you control, except the token has flying and it isn't legendary.

Gigantoplasm

You may have Gigantoplasm enter the battlefield as a copy of any creature on the battlefield, except it has "{X}: This creature has base power and toughness X/X."

Ghastly Mimicry

Enchant creature
At the beginning of your upkeep, create a token that's a copy of enchanted creature, except it's a Spirit in addition to its other types.
If Ghastly Mimicry would be put into a graveyard from anywhere, exile it instead.

Mirrorhall Mimic

You may have Mirrorhall Mimic enter the battlefield as a copy of any creature on the battlefield, except it's a Spirit in addition to its other types.
Disturb {3}{U}{U} (You may cast this card from your graveyard transformed for its disturb cost.)

Mirrorhall Mimic // Ghastly Mimicry

Quasiduplicate

Create a token that's a copy of target creature you control.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Phyrexian Metamorph

({U/P} can be paid with either {U} or 2 life.)
You may have Phyrexian Metamorph enter the battlefield as a copy of any artifact or creature on the battlefield, except it's an artifact in addition to its other types.

Mirrormade

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

Phantasmal Image

You may have Phantasmal Image enter the battlefield as a copy of any creature on the battlefield, except it's an Illusion in addition to its other types and it has "When this creature becomes the target of a spell or ability, sacrifice it."

Undercity Sewers

({T}: Add {U} or {B}.)
Undercity Sewers enters the battlefield tapped.
When Undercity Sewers enters the battlefield, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Wrong Turn

Target opponent gains control of target creature. (If an attacking or blocking creature changes controllers, it's removed from combat.)

Blade of Selves

Equipped creature has myriad. (Whenever it attacks, for each opponent other than defending player, you may create a token that's a copy of that creature that's tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)
Equip {4}

Malcolm, Alluring Scoundrel

Flash
Flying
Whenever Malcolm, Alluring Scoundrel deals combat damage to a player, put a chorus counter on it. Draw a card, then discard a card. If there are four or more chorus counters on Malcolm, you may cast the discarded card without paying its mana cost.

Sepulchral Primordial

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
When Sepulchral Primordial enters the battlefield, for each opponent, you may put up to one target creature card from that player's graveyard onto the battlefield under your control.

Breach the Multiverse

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

Conspiracy Unraveler

Flying
You may collect evidence 10 rather than pay the mana cost for spells that you cast. (To collect evidence 10, exile cards with total mana value 10 or greater from your graveyard.)

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Halo Forager

Flying
When Halo Forager enters the battlefield, you may pay {X}. When you do, you may cast target instant or sorcery card with mana value X from a graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

Undercover Butler

Whenever Undercover Butler attacks the player with the most life or tied for most life, it can't be blocked this turn.

Quantum Misalignment

Create a token that's a copy of target creature you control, except it isn't legendary.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)

Spark Double

You may have Spark Double enter the battlefield as a copy of a creature or planeswalker you control, except it enters with an additional +1/+1 counter on it if it's a creature, it enters with an additional loyalty counter on it if it's a planeswalker, and it isn't legendary.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad, the Grim deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Evil Twin

You may have Evil Twin enter the battlefield as a copy of any creature on the battlefield, except it has "{U}{B}, {T}: Destroy target creature with the same name as this creature."

Auton Soldier

You may have Auton Soldier enter the battlefield as a copy of any creature on the battlefield, except it isn't legendary, is an artifact in addition to its other types, and has myriad. (Whenever it attacks, for each opponent other than defending player, you may put a token that's a copy of this creature onto the battlefield tapped and attacking that player or a planeswalker they control. Exile the tokens at end of combat.)