Pitiless Carnage

Sacrifice any number of permanents you control, then draw that many cards.
Plot {1}{B}{B} (You may pay {1}{B}{B} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Eris, Roar of the Storm

This spell costs {2} less to cast for each different mana value among instant and sorcery cards in your graveyard.
Flying, prowess
Whenever you cast your second spell each turn, create a 4/4 red Dragon Elemental creature token with flying and prowess.

Poxwalkers

Deathtouch
Curse of the Walking Pox — Whenever you cast a spell from anywhere other than your hand, return this card from your graveyard to the battlefield tapped.

Grab the Prize

As an additional cost to cast this spell, discard a card.
Draw two cards. If the discarded card wasn't a land card, Grab the Prize deals 2 damage to each opponent.

Impending Flux

Paradox — Impending Flux deals X damage to each opponent and each creature they control, where X is 1 plus the number of spells you've cast from anywhere other than your hand this turn.
Foretell {1}{R}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Slickshot Lockpicker

When this creature enters, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)
Plot {2}{U} (You may pay {2}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Backlash

Tap target untapped creature. That creature deals damage equal to its power to its controller.

Diminishing Returns

Each player shuffles their hand and graveyard into their library. You exile the top ten cards of your library. Then each player draws up to seven cards.

Surge of Brilliance

Paradox — Draw a card for each spell you've cast this turn from anywhere other than your hand.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Cornered by Black Mages

Target opponent sacrifices a creature of their choice.
Create a 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent."

Circle of Power

You draw two cards and you lose 2 life. Create a 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent."
Wizards you control get +1/+0 and gain lifelink until end of turn.

Wild-Magic Sorcerer

The first spell you cast from exile each turn has cascade. (When you cast your first spell from exile, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Transpose

Draw a card, then discard a card. You lose 1 life. If this spell was cast from your hand, create a 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent."
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.)

Sol Ring

Step Between Worlds

Each player may shuffle their hand and graveyard into their library. Each player who does draws seven cards. Exile Step Between Worlds.
Plot {4}{U}{U} (You may pay {4}{U}{U} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Abaddon the Despoiler

Trample
Mark of Chaos Ascendant — During your turn, spells you cast from your hand with mana value X or less have cascade, where X is the total amount of life your opponents have lost this turn.

Ultimate Magic: Meteor

Ultimate Magic: Meteor deals 7 damage to each creature. If this spell was cast from exile, for each opponent, choose an artifact or land that player controls. Destroy the chosen permanents.
Foretell {5}{R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Have

Iraxxa, Empress of Mars

Trample
Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)
Paradox — Whenever you cast a spell from anywhere other than your hand, create a 2/2 red Alien Warrior creature token.

Mage Siege

Create a 0/1 black Wizard creature token with "Whenever you cast a noncreature spell, this token deals 1 damage to each opponent."