Slip Out the Back

Put a +1/+1 counter on target creature. It phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Thought Scour

Target player mills two cards.
Draw a card.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Young Pyromancer

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

Island

Living End

Suspend 3—{2}{B}{B}
Each player exiles all creature cards from their graveyard, then sacrifices all creatures they control, then puts all cards they exiled this way onto the battlefield.

Eye of the Storm

Whenever a player casts an instant or sorcery card, exile it. Then that player copies each instant or sorcery card exiled with this enchantment. For each copy, the player may cast the copy without paying its mana cost.

Dragon's Rage Channeler

Whenever you cast a noncreature spell, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
Delirium — As long as there are four or more card types among cards in your graveyard, Dragon's Rage Channeler gets +2/+2, has flying, and attacks each combat if able.

Thousand-Year Storm

Whenever you cast an instant or sorcery spell, copy it for each other instant and sorcery spell you've cast before it this turn. You may choose new targets for the copies.

Otherworldly Gaze

Surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Dreadhorde Arcanist

Trample
Whenever this creature attacks, you may cast target instant or sorcery card with mana value less than or equal to this creature's power from your graveyard without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Mountain

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Tome Scour

Ancestral Vision

Suspend 4—{U} (Rather than cast this card from your hand, pay {U} and exile it with four time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Target player draws three cards.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Treasure Cruise

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Draw three cards.

Consider

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

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Flame Jab

Flame Jab deals 1 damage to any target.
Retrace (You may cast this card from your graveyard by discarding a land card in addition to paying its other costs.)

Crashing Footfalls

Suspend 4—{G} (Rather than cast this card from your hand, pay {G} and exile it with four time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Create two 4/4 green Rhino creature tokens with trample.

Monastery Swiftspear

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Expressive Iteration

Look at the top three cards of your library. Put one of them into your hand, put one of them on the bottom of your library, and exile one of them. You may play the exiled card this turn.

Awoken Horror

When this creature transforms into Awoken Horror, return all non-Horror creatures to their owners' hands.

Thing in the Ice

Defender
This creature enters with four ice counters on it.
Whenever you cast an instant or sorcery spell, remove an ice counter from this creature. Then if it has no ice counters on it, transform it.