Clockspinning

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Choose a counter on target permanent or suspended card. Remove that counter from that permanent or card or put another of those counters on it.

Electrostatic Infantry

Trample
Whenever you cast an instant or sorcery spell, put a +1/+1 counter on Electrostatic Infantry.

Cerulean Wisps

Target creature becomes blue until end of turn. Untap that creature.
Draw a card.

Mountain

Thought Scour

Target player mills two cards.
Draw a card.

Dramatic Reversal

Untap all nonland permanents you control.

Prismari Pledgemage

Defender
Magecraft — Whenever you cast or copy an instant or sorcery spell, Prismari Pledgemage can attack this turn as though it didn't have defender.

Counterspell

Expedite

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

Island

Abrade

Choose one —
• Abrade deals 3 damage to target creature.
• Destroy target artifact.

Frostboil Snarl

As Frostboil Snarl enters the battlefield, you may reveal an Island or Mountain card from your hand. If you don't, Frostboil Snarl enters the battlefield tapped.
{T}: Add {U} or {R}.

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

Sprite Dragon

Flying, haste
Whenever you cast a noncreature spell, put a +1/+1 counter on Sprite Dragon.

Blustersquall

Tap target creature you don't control.
Overload {3}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Raze the Effigy

Choose one —
• Destroy target artifact.
• Target attacking creature gets +2/+2 until end of turn.

Chain to Memory

Target creature gets -4/-0 until end of turn. Scry 2.

Brute Force

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

Force of Rage

If it's not your turn, you may exile a red card from your hand rather than pay this spell's mana cost.
Create two 3/1 red Elemental creature tokens with trample and haste. Sacrifice those tokens at the beginning of your next upkeep.

Balmor, Battlemage Captain

Flying
Whenever you cast an instant or sorcery spell, creatures you control get +1/+0 and gain trample until end of turn.