Arcane Investigator

Search the Room — {5}{U}: Roll a d20.
1—9 | Draw a card.
10—20 | Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Aberrant Mind Sorcerer

Psionic Spells — When Aberrant Mind Sorcerer enters, choose target instant or sorcery card in your graveyard, then roll a d20.
1—9 | You may put that card on top of your library.
10—20 | Return that card to your hand.

Ancient Copper Dragon

Flying
Whenever Ancient Copper Dragon deals combat damage to a player, roll a d20. You create a number of Treasure tokens equal to the result.

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.

Earth-Cult Elemental

Siege Monster — When Earth-Cult Elemental enters, roll a d20.
1—9 | Each player sacrifices a permanent of their choice.
10—19 | Each opponent sacrifices a permanent of their choice.
20 | Each opponent sacrifices two permanents of their choice.

Goblin Morningstar

Equipped creature gets +1/+0 and has trample.
Equip {1}{R}
When Goblin Morningstar enters, roll a d20.
1—9 | Create a 1/1 red Goblin creature token.
10—20 | Create a 1/1 red Goblin creature token, then attach Goblin Morningstar to it.

Ancient Silver Dragon

Flying
Whenever Ancient Silver Dragon deals combat damage to a player, roll a d20. Draw cards equal to the result. You have no maximum hand size for the rest of the game.

The Deck of Many Things

{2}, {T}: Roll a d20 and subtract the number of cards in your hand. If the result is 0 or less, discard your hand.
1—9 | Return a card at random from your graveyard to your hand.
10—19 | Draw two cards.
20 | Put a creature card from any graveyard onto the battlefield under your control. When that creature dies, its owner loses the game.

Hoarding Ogre

Whenever Hoarding Ogre attacks, roll a d20.
1—9 | Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
10—19 | Create two Treasure tokens.
20 | Create three Treasure tokens.

Chaos Channeler

Wild Magic Surge — Whenever Chaos Channeler attacks, roll a d20.
1—9 | Exile the top card of your library. You may play it this turn.
10—19 | Exile the top two cards of your library. You may play them this turn.
20 | Exile the top three cards of your library. You may play them this turn.

Barbarian Class

(Gain the next level as a sorcery to add its ability.)
If you would roll one or more dice, instead roll that many dice plus one and ignore the lowest roll.
{1}{R}: Level 2
Whenever you roll one or more dice, target creature you control gets +2/+0 and gains menace until end of turn.
{2}{R}: Level 3
Creatures you control have haste.

Djinni Windseer

Flying
When Djinni Windseer enters, roll a d20.
1—9 | Scry 1.
10—19 | Scry 2.
20 | Scry 3.

Scion of Stygia

Flash
Cone of Cold — When Scion of Stygia enters, choose target creature an opponent controls, then roll a d20.
1—9 | Tap that creature.
10—20 | Tap that creature. It doesn't untap during its controller's next untap step.

Delina, Wild Mage

Whenever Delina, Wild Mage attacks, choose target creature you control, then roll a d20.
1—14 | Create a tapped and attacking token that's a copy of that creature, except it's not legendary and it has "At end of combat, exile this creature."
15—20 | Create one of those tokens. You may roll again.

Spiked Pit Trap

Flash
{5}, {T}, Sacrifice Spiked Pit Trap: Choose target creature, then roll a d20.
1—9 | Spiked Pit Trap deals 5 damage to that creature.
10—20 | Spiked Pit Trap deals 5 damage to that creature. Create a Treasure token.

Power of Persuasion

Choose target creature an opponent controls, then roll a d20.
1—9 | Return it to its owner's hand.
10—19 | Its owner puts it on their choice of the top or bottom of their library.
20 | Gain control of it until the end of your next turn.

Treasure Chest

{4}, Sacrifice Treasure Chest: Roll a d20.
1 | Trapped! — You lose 3 life.
2—9 | Create five Treasure tokens.
10—19 | You gain 3 life and draw three cards.
20 | Search your library for a card. If it's an artifact card, you may put it onto the battlefield. Otherwise, put that card into your hand. Then shuffle.

Feywild Trickster

Whenever you roll one or more dice, create a 1/1 blue Faerie Dragon creature token with flying.

Gale's Redirection

Exile target spell, then roll a d20 and add that spell's mana value.
1—14 | You may cast the exiled card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.
15+ | You may cast the exiled card without paying its mana cost for as long as it remains exiled.

Wizard's Spellbook

{T}: Exile target instant or sorcery card from a graveyard. Roll a d20. Activate only as a sorcery.
1—9 | Copy that card. You may cast the copy.
10—19 | Copy that card. You may cast the copy by paying {1} rather than paying its mana cost.
20 | Copy each card exiled with Wizard's Spellbook. You may cast any number of the copies without paying their mana costs.

Farideh, Devil's Chosen

Dark One's Own Luck — Whenever you roll one or more dice, Farideh, Devil's Chosen gains flying and menace until end of turn. If any of those results was 10 or higher, draw a card.

Swarming Goblins

When Swarming Goblins enters, roll a d20.
1—9 | Create a 1/1 red Goblin creature token.
10—19 | Create two of those tokens.
20 | Create three of those tokens.