Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Voracious Reader

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Instant and sorcery spells you cast cost {1} less to cast.

Curious Homunculus

{T}: Add {C}. Spend this mana only to cast an instant or sorcery spell.
At the beginning of your upkeep, if there are three or more instant and/or sorcery cards in your graveyard, transform Curious Homunculus.

Curious Homunculus // Voracious Reader

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Fierce Guardianship

If you control a commander, you may cast this spell without paying its mana cost.
Counter target noncreature spell.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Single Combat

Each player chooses a creature or planeswalker they control, then sacrifices the rest. Players can't cast creature or planeswalker spells until the end of your next turn.

Vega, the Watcher

Flying
Whenever you cast a spell from anywhere other than your hand, draw a card.

Shadow Rift

Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)
Draw a card.

Snap

Return target creature to its owner's hand. Untap up to two lands.

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Archmage Emeritus

Magecraft — Whenever you cast or copy an instant or sorcery spell, draw a card.

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Zethi, Arcane Blademaster

Multikicker {W/U}
When Zethi, Arcane Blademaster enters, exile up to X target instant cards from your graveyard, where X is the number of times Zethi was kicked. Put a kick counter on each of them.
Whenever Zethi attacks, copy each exiled card you own with a kick counter on it. You may cast the copies.