Demogorgon's Clutches

Target opponent discards two cards, mills two cards, and loses 2 life. (To mill a card, a player puts the top card of their library into their graveyard.)

Contact Other Plane

Roll a d20.
1—9 | Draw two cards.
10—19 | Scry 2, then draw two cards.
20 | Scry 3, then draw three cards.

Island

Eyes of the Beholder

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

Mordenkainen

+2: Draw two cards, then put a card from your hand on the bottom of your library.
−2: Create a blue Dog Illusion creature token with "This creature's power and toughness are each equal to twice the number of cards in your hand."
−10: Exchange your hand and library, then shuffle. You get an emblem with "You have no maximum hand size."

Precipitous Drop

Enchant creature
When Precipitous Drop enters, venture into the dungeon. (Enter the first room or advance to the next room.)
Enchanted creature gets -2/-2. It gets -5/-5 instead as long as you've completed a dungeon.

Black Dragon

Flying
Acid Breath — When Black Dragon enters, target creature an opponent controls gets -3/-3 until end of turn.

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.

Swamp

Bar the Gate

Counter target creature or planeswalker spell. Venture into the dungeon. (Enter the first room or advance to the next room.)

Silver Raven

Flying
When Silver Raven enters, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Trickster's Talisman

Invoke Duplicity — Equipped creature gets +1/+1 and has "Whenever this creature deals combat damage to a player, you may sacrifice Trickster's Talisman. If you do, create a token that's a copy of this creature."
Equip {2}

Shambling Ghast

When Shambling Ghast dies, choose one —
• Brave the Stench — Target creature an opponent controls gets -1/-1 until end of turn.
• Search the Body — Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Rogue Class

(Gain the next level as a sorcery to add its ability.)
Whenever a creature you control deals combat damage to a player, exile the top card of that player's library face down. You may look at it for as long as it remains exiled.
{1}{U}{B}: Level 2
Creatures you control have menace.
{2}{U}{B}: Level 3
You may play cards exiled with Rogue Class, and you may spend mana as though it were mana of any color to cast those spells.

Manticore

Flash
Flying
Tail Spikes — When Manticore enters, destroy target creature an opponent controls that was dealt damage this turn.

Soulknife Spy

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

Zombie Ogre

At the beginning of your end step, if a creature died this turn, venture into the dungeon. (Enter the first room or advance to the next room.)

Power Word Kill

Destroy target non-Angel, non-Demon, non-Devil, non-Dragon creature.

Charmed Sleep

Enchant creature
When Charmed Sleep enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

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.")

You Find the Villains' Lair

Choose one —
• Foil Their Scheme — Counter target spell.
• Learn Their Secrets — Draw two cards, then discard two cards.