Titan's Strength

Target creature gets +3/+1 until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Assault Strobe

Target creature gains double strike until end of turn. (It deals both first-strike and regular combat damage.)

Brute Force

Target creature gets +3/+3 until end of turn.

Seize the Day

Untap target creature. After this main phase, there is an additional combat phase followed by an additional main phase.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Accelerate

Target creature gains haste until end of turn.
Draw a card.

Expedite

Tail Slash

Target creature you control deals damage equal to its power to target creature you don't control.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Zap deals 1 damage to any target.
Draw a card.

Doublecast

When you next cast an instant or sorcery spell this turn, copy that spell. You may choose new targets for the copy.

Otherworldly Outburst

Target creature gets +1/+0 until end of turn. When that creature dies this turn, create a 3/2 colorless Eldrazi Horror creature token.

Mages' Contest

You and target spell's controller bid life. You start the bidding with a bid of 1. In turn order, each player may top the high bid. The bidding ends if the high bid stands. The high bidder loses life equal to the high bid. If you win the bidding, counter that spell.

Bonus Round

Until end of turn, whenever a player casts an instant or sorcery spell, that player copies it and may choose new targets for the copy.

Transmogrify

Exile target creature. That creature's controller reveals cards from the top of their library until they reveal a creature card. That player puts that card onto the battlefield, then shuffles the rest into their library.

Zada, Hedron Grinder

Whenever you cast an instant or sorcery spell that targets only Zada, copy that spell for each other creature you control that the spell could target. Each copy targets a different one of those creatures.

Infuriate

Target creature gets +3/+2 until end of turn.

Mizzix's Mastery

Exile target card that's an instant or sorcery from your graveyard. For each card exiled this way, copy it, and you may cast the copy without paying its mana cost. Exile Mizzix's Mastery.
Overload {5}{R}{R}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Samut's Sprint

Target creature gets +2/+1 and gains haste until end of turn. Scry 1.

Spawning Breath

Spawning Breath deals 1 damage to any target. Create a 0/1 colorless Eldrazi Spawn creature token. It has "Sacrifice this token: Add {C}."

Unleash Fury

Double the power of target creature until end of turn.

Harmless Offering

Target opponent gains control of target permanent you control.

Built to Smash

Target attacking creature gets +3/+3 until end of turn. If it's an artifact creature, it gains trample until end of turn.

Storm Strike

Target creature gets +1/+0 and gains first strike until end of turn. Scry 1.

Boiling Blood

Target creature attacks this turn if able.
Draw a card.

Stun

Target creature can't block this turn.
Draw a card.

Krark, the Thumbless

Whenever you cast an instant or sorcery spell, flip a coin. If you lose the flip, return that spell to its owner's hand. If you win the flip, copy that spell, and you may choose new targets for the copy.
Partner (You can have two commanders if both have partner.)

Arcbond

Choose target creature. Whenever that creature is dealt damage this turn, it deals that much damage to each other creature and each player.

Renegade Tactics

Rile

Rile deals 1 damage to target creature you control. That creature gains trample until end of turn.
Draw a card.

Shreds of Sanity

Return up to one target instant card and up to one target sorcery card from your graveyard to your hand, then discard a card. Exile Shreds of Sanity.

Kari Zev's Expertise

Gain control of target creature or Vehicle until end of turn. Untap it. It gains haste until end of turn.
You may cast a spell with mana value 2 or less from your hand without paying its mana cost.

Temur Battle Rage

Target creature gains double strike until end of turn.
Ferocious — That creature also gains trample until end of turn if you control a creature with power 4 or greater.

Balduvian Rage

Target attacking creature gets +X/+0 until end of turn.
Draw a card at the beginning of the next turn's upkeep.

Fists of Flame

Draw a card. Until end of turn, target creature gains trample and gets +1/+0 for each card you've drawn this turn. (A creature with trample can deal excess combat damage to the player or planeswalker it's attacking.)

Make Mischief

Make Mischief deals 1 damage to any target. Create a 1/1 red Devil creature token. It has "When this token dies, it deals 1 damage to any target."

Arc Lightning

Arc Lightning deals 3 damage divided as you choose among one, two, or three targets.