Hydrosurge

Target creature gets -5/-0 until end of turn.

Jeskai Elder

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever this creature deals combat damage to a player, you may draw a card. If you do, discard a card.

Island

Snap

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

Silver Myr

Quandrix Pledgemage

Magecraft — Whenever you cast or copy an instant or sorcery spell, put a +1/+1 counter on this creature.

Planar Incision

Exile target artifact or creature, then return it to the battlefield under its owner's control with a +1/+1 counter on it.

Consider

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
Draw a card.

Jhessian Thief

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever this creature deals combat damage to a player, draw a card.

Deep Analysis

Target player draws two cards.
Flashback—{1}{U}, Pay 3 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Counterspell

Capsize

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.)
Return target permanent to its owner's hand.

Ingenious Skaab

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
{U}: This creature gets +1/-1 until end of turn.

Tolarian Terror

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.
Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.)

Dramatic Reversal

Untap all nonland permanents you control.

Insectile Aberration

Delver of Secrets

At the beginning of your upkeep, look at the top card of your library. You may reveal that card. If an instant or sorcery card is revealed this way, transform this creature.

Delver of Secrets // Insectile Aberration

Defy Gravity

Target creature gains flying until end of turn.
Flashback {U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)