Retrieve Prey

Exile target creature card from your graveyard. Until the end of your next turn, you may cast that card. (Then exile this card. You may cast the creature later from exile.)

Tlincalli Hunter

Trample
Once each turn, you may pay {0} rather than pay the mana cost for a creature spell you cast from exile.

Tlincalli Hunter // Retrieve Prey

Kellan Joins Up

When Kellan Joins Up enters, you may exile a nonland card with mana value 3 or less from your hand. If you do, it becomes plotted. (You may cast it as a sorcery on a later turn without paying its mana cost.)
Whenever a legendary creature you control enters, put a +1/+1 counter on each creature you control.

Monk Class

(Gain the next level as a sorcery to add its ability.)
The second spell you cast each turn costs {1} less to cast.
{W}{U}: Level 2
When this Class becomes level 2, return up to one target nonland permanent to its owner's hand.
{1}{W}{U}: Level 3
At the beginning of your upkeep, exile the top card of your library. For as long as it remains exiled, it has "You may cast this card from exile as long as you've cast another spell this turn."

Vega, the Watcher

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

Surge of Brilliance

Paradox — Draw a card for each spell you've cast this turn from anywhere other than your hand.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Savvy Trader

When Savvy Trader enters, exile target permanent card from your graveyard. You may play that card for as long as it remains exiled.
Spells you cast from anywhere other than your hand cost {1} less to cast.

The Foretold Soldier

The Foretold Soldier must be blocked if able.
The Foretold Soldier can't be blocked by more than one creature.
Whenever The Foretold Soldier deals damage, exile it face down. It becomes foretold.
Foretell {1}{G} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Ellie and Alan, Paleontologists

{T}, Exile a creature card from your graveyard: Discover X, where X is the mana value of the exiled card. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with that mana value or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Hidden Courtyard

Hidden Courtyard enters tapped.
{T}: Add {W}.
{4}{W}, {T}, Sacrifice Hidden Courtyard: Discover 4. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Sisterhood of Karn

Sisterhood of Karn enters with a +1/+1 counter on it.
Paradox — Whenever you cast a spell from anywhere other than your hand, double the number of +1/+1 counters on Sisterhood of Karn.

Oracle's Vault

{2}, {T}: Exile the top card of your library. Until end of turn, you may play that card. Put a brick counter on Oracle's Vault.
{T}: Exile the top card of your library. Until end of turn, you may play that card without paying its mana cost. Activate only if there are three or more brick counters on Oracle's Vault.

Forest

Mosswort Bridge

Hideaway 4 (When this land enters, look at the top four cards of your library, exile one face down, then put the rest on the bottom in a random order.)
Mosswort Bridge enters tapped.
{T}: Add {G}.
{G}, {T}: You may play the exiled card without paying its mana cost if creatures you control have total power 10 or greater.

Island

Hidden Nursery

Hidden Nursery enters tapped.
{T}: Add {G}.
{4}{G}, {T}, Sacrifice Hidden Nursery: Discover 4. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Doc Aurlock, Grizzled Genius

Spells you cast from your graveyard or from exile cost {2} less to cast.
Plotting cards from your hand costs {2} less.

Imoti, Celebrant of Bounty

Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)
Spells you cast with mana value 6 or greater have cascade.

Hidden Cataract

Hidden Cataract enters tapped.
{T}: Add {U}.
{4}{U}, {T}, Sacrifice Hidden Cataract: Discover 4. Activate only as a sorcery. (Exile cards from the top of your library until you exile a nonland card with mana value 4 or less. Cast it without paying its mana cost or put it into your hand. Put the rest on the bottom in a random order.)

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Magus of the Mind

{U}, {T}, Sacrifice Magus of the Mind: Shuffle your library, then exile the top X cards, where X is one plus the number of spells cast this turn. Until end of turn, you may play lands and cast spells from among cards exiled this way without paying their mana costs.

Seaside Citadel

Seaside Citadel enters tapped.
{T}: Add {G}, {W}, or {U}.

Plains

Break Down

Destroy target artifact or enchantment. Create a Junk token. (It's an artifact with "{T}, Sacrifice this artifact: Exile the top card of your library. You may play that card this turn. Activate only as a sorcery.")

Sage of the Beyond

Flying
Spells you cast from anywhere other than your hand cost {2} less to cast.
Foretell {4}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Rashmi, Eternities Crafter

Whenever you cast your first spell each turn, reveal the top card of your library. You may cast it without paying its mana cost if it's a spell with lesser mana value. If you don't cast it, put it into your hand.

Apex Devastator

Cascade, cascade, cascade, cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order. Multiple instances of cascade each trigger separately.)

River Song's Diary

Imprint — Whenever a player casts an instant or sorcery spell from their hand, exile it instead of putting it into a graveyard as it resolves.
At the beginning of your upkeep, if there are four or more cards exiled with River Song's Diary, choose one of them at random. You may cast it without paying its mana cost.

Kellan, the Kid

Flying, lifelink
Whenever you cast a spell from anywhere other than your hand, you may cast a permanent spell with equal or lesser mana value from your hand without paying its mana cost. If you don't, you may put a land card from your hand onto the battlefield.

Deep-Sea Kraken

Deep-Sea Kraken can't be blocked.
Suspend 9—{2}{U} (Rather than cast this card from your hand, you may pay {2}{U} and exile it with nine 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. It has haste.)
Whenever an opponent casts a spell, if Deep-Sea Kraken is suspended, remove a time counter from it.

Saw It Coming

Counter target spell.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Kayla's Music Box

{W}, {T}: Look at the top card of your library, then exile it face down. (You may look at it any time.)
{T}: Until end of turn, you may play cards you own exiled with Kayla's Music Box.