Mordenkainen's Polymorph

Until end of turn, target creature becomes a Dragon with base power and toughness 4/4 and gains flying. (It loses all other creature types.)

Vorpal Sword

Equipped creature gets +2/+0 and has deathtouch.
{5}{B}{B}{B}: Until end of turn, Vorpal Sword gains "Whenever equipped creature deals combat damage to a player, that player loses the game."
Equip {B}{B}

Tizerus Charger

Escape—{4}{B}, Exile five other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Tizerus Charger escapes with your choice of a +1/+1 counter or a flying counter on it.

Skittering Heartstopper

{B}: Skittering Heartstopper gains deathtouch until end of turn.

Mistwalker

Changeling (This card is every creature type.)
Flying
{1}{U}: Mistwalker gets +1/-1 until end of turn.

Thieves' Tools

When Thieves' Tools enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Equipped creature can't be blocked as long as its power is 3 or less.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Meteorite

When Meteorite enters, it deals 2 damage to any target.
{T}: Add one mana of any color.

Scalding Cauldron

{3}, {T}, Sacrifice Scalding Cauldron: It deals 3 damage to target creature.

Nevinyrral's Disk

Nevinyrral's Disk enters tapped.
{1}, {T}: Destroy all artifacts, creatures, and enchantments.

Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Yuan-Ti Malison

Yuan-Ti Malison can't be blocked as long as it's attacking alone.
Whenever Yuan-Ti Malison deals combat damage to a player, venture into the dungeon. (Enter the first room or advance to the next room.)

Mystic Sanctuary

({T}: Add {U}.)
Mystic Sanctuary enters tapped unless you control three or more other Islands.
When Mystic Sanctuary enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Acererak the Archlich

When Acererak the Archlich enters, if you haven't completed Tomb of Annihilation, return Acererak the Archlich to its owner's hand and venture into the dungeon.
Whenever Acererak the Archlich attacks, for each opponent, you create a 2/2 black Zombie creature token unless that player sacrifices a creature of their choice.

Spreading Rot

Destroy target land. Its controller loses 2 life.

Vraska's Finisher

When Vraska's Finisher enters, destroy target creature or planeswalker an opponent controls that was dealt damage this turn.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Turn to Frog

Until end of turn, target creature loses all abilities and becomes a blue Frog with base power and toughness 1/1.

Persist

Return target nonlegendary creature card from your graveyard to the battlefield with a -1/-1 counter on it.

Scourge of Fleets

When Scourge of Fleets enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Murder

Coral Barrier

Defender (This creature can't attack.)
When Coral Barrier enters, create a 1/1 blue Squid creature token with islandwalk. (It can't be blocked as long as defending player controls an Island.)

Pin to the Earth

Enchant creature
Enchanted creature gets -6/-0.

Soulknife Spy

Whenever Soulknife Spy deals combat damage to a player, draw a card.

Seal of Removal

Sacrifice Seal of Removal: Return target creature to its owner's hand.

Guild Thief

Whenever Guild Thief deals combat damage to a player, put a +1/+1 counter on it.
Cunning Action — {3}{U}: Guild Thief can't be blocked this turn.

Amphin Cutthroat

Hubris

Return target creature and all Auras attached to it to their owners' hands.

Furtive Homunculus

Skulk (This creature can't be blocked by creatures with greater power.)

Suspend

Exile target creature and put two time counters on it. If it doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, they may play it without paying its mana cost. If it's a creature, it has haste.)

Hoard Robber

Whenever Hoard Robber deals combat damage to a player, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Explosive Apparatus

{3}, {T}, Sacrifice Explosive Apparatus: It deals 2 damage to any target.

Mind Rot

Jace's Sanctum

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, scry 1.

Cast into Darkness

Enchant creature
Enchanted creature gets -2/-0 and can't block.

Feed the Serpent

Go Blank

Target player discards two cards. Then exile that player's graveyard.

Liliana's Indignation

Mill X cards. Target player loses 2 life for each creature card put into your graveyard this way.

Omniscience

You may cast spells from your hand without paying their mana costs.

Skirge Familiar

Prying Questions

Target opponent loses 3 life and puts a card from their hand on top of their library.

Felhide Petrifier

Deathtouch
Other Minotaur creatures you control have deathtouch.

Counterspell

Prismite

Banehound

Throwing Knife

Equipped creature gets +2/+0.
Whenever equipped creature attacks, you may sacrifice Throwing Knife. If you do, Throwing Knife deals 2 damage to any target.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Blood Reckoning

Whenever a creature attacks you or a planeswalker you control, that creature's controller loses 1 life.

Island

Consign to the Pit

Destroy target creature. Consign to the Pit deals 2 damage to that creature's controller.

Rancid Rats

Skulk (This creature can't be blocked by creatures with greater power.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Countermand

Counter target spell. Its controller mills four cards.

Spiteful Blow

Krydle of Baldur's Gate

Whenever Krydle of Baldur's Gate deals combat damage to a player, that player loses 1 life and mills a card, then you gain 1 life and scry 1.
Whenever you attack, you may pay {2}. If you do, target creature can't be blocked this turn.

Swamp

Succumb to Temptation

Eyes of the Beholder

Target creature gets -11/-11 until end of turn.

Thieves' Guild Enforcer

Flash
Whenever Thieves' Guild Enforcer or another Rogue you control enters, each opponent mills two cards.
As long as an opponent has eight or more cards in their graveyard, Thieves' Guild Enforcer gets +2/+1 and has deathtouch.

Wormhole Serpent

{3}{U}: Target creature can't be blocked this turn.

Rabid Bloodsucker

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Rabid Bloodsucker enters, each player loses 2 life.

Hall of Storm Giants

If you control two or more other lands, Hall of Storm Giants enters tapped.
{T}: Add {U}.
{5}{U}: Until end of turn, Hall of Storm Giants becomes a 7/7 blue Giant creature with ward {3}. It's still a land. (Whenever it becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.)

Dress Down

Flash
When Dress Down enters, draw a card.
Creatures lose all abilities.
At the beginning of the end step, sacrifice Dress Down.

Harrowing Journey

Target player draws three cards and loses 3 life.

Blue Dragon

Flying
Lightning Breath — When Blue Dragon enters, until your next turn, target creature an opponent controls gets -3/-0, up to one other target creature gets -2/-0, and up to one other target creature gets -1/-0.

Wight

Wight enters tapped.
Life Drain — Whenever a creature dealt damage by Wight this turn dies, create a tapped 2/2 black Zombie creature token and exile that card.

Shimmerdrift Vale

Shimmerdrift Vale enters tapped.
As Shimmerdrift Vale enters, choose a color.
{T}: Add one mana of the chosen color.

Tasha's Hideous Laughter

Each opponent exiles cards from the top of their library until that player has exiled cards with total mana value 20 or more.

Ornithopter of Paradise

Sea Drake

Flying
When Sea Drake enters, return two target lands you control to their owner's hand.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Witch's Cottage

({T}: Add {B}.)
Witch's Cottage enters tapped unless you control three or more other Swamps.
When Witch's Cottage enters untapped, you may put target creature card from your graveyard on top of your library.

Vampire Opportunist

{6}{B}: Each opponent loses 2 life and you gain 2 life.

Humongulus

Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Silent Dart

{4}, {T}, Sacrifice Silent Dart: It deals 3 damage to target creature.

Pharika's Chosen

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Warlock Class

(Gain the next level as a sorcery to add its ability.)
At the beginning of your end step, if a creature died this turn, each opponent loses 1 life.
{1}{B}: Level 2
When this Class becomes level 2, look at the top three cards of your library. Put one of them into your hand and the rest into your graveyard.
{6}{B}: Level 3
At the beginning of your end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)