Monstrous Vortex

Whenever you cast a creature spell with power 5 or greater, discover X, where X is that spell's mana value. (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.)

Forest

Authority

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Tap up to two target creatures your opponents control. Creatures you control gain vigilance until end of turn.

Appeal

Until end of turn, target creature gains trample and gets +X/+X, where X is the number of creatures you control.

Appeal // Authority

Rob the Hoard

Return target artifact, enchantment, or legendary card from your graveyard to your hand. (Then exile this card. You may cast the creature later from exile.)

Crystal Dragon

Crystal Dragon // Rob the Hoard

The Temporal Anchor

At the beginning of your upkeep, scry 2.
Whenever you choose to put one or more cards on the bottom of your library while scrying, exile that many cards from the bottom of your library.
During your turn, you may play cards exiled with The Temporal Anchor.

Psionic Pulse

Counter target noncreature spell. (Then exile this card. You may cast the creature later from exile.)

Sapphire Dragon

Flying
Whenever Sapphire Dragon attacks or blocks, scry 2.

Sapphire Dragon // Psionic Pulse

Bring Back

Create two 1/1 white Human creature tokens. (Then exile this card. You may cast the creature later from exile.)

Oakhame Ranger

{T}: Creatures you control get +1/+1 until end of turn.

Oakhame Ranger // Bring Back

Ardenvale Fealty

Create a 2/2 white Knight creature token with vigilance. (Then exile this card. You may cast the enchantment later from exile.)

Virtue of Loyalty

At the beginning of your end step, put a +1/+1 counter on each creature you control. Untap those creatures.

Virtue of Loyalty // Ardenvale Fealty

Mysterious Pathlighter

Flying
Each creature you control that has an Adventure enters with an additional +1/+1 counter on it. (It doesn't need to have gone on the adventure first.)

Ysgard's Call

Create X 1/1 white Soldier creature tokens. (Then exile this card. You may cast the artifact later from exile.)

Horn of Valhalla

Equipped creature gets +1/+1 for each creature you control.
Equip {3}

Horn of Valhalla // Ysgard's Call

Abzan Falconer

Outlast {W} ({W}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has flying.

Sailors' Bane

This spell costs {1} less to cast for each card you own in exile and in your graveyard that's an instant card, a sorcery card, or a card that has an Adventure.
Ward {4} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {4}.)

Taigam, Ojutai Master

Instant, sorcery, and Dragon spells you control can't be countered.
Whenever you cast an instant or sorcery spell from your hand, if Taigam, Ojutai Master attacked this turn, that spell gains rebound. (Exile the spell as it resolves. At the beginning of your next upkeep, you may cast that card from exile without paying its mana cost.)

Aquatic Ingress

Up to two target creatures each get +1/+0 until end of turn and can't be blocked this turn. (Then exile this card. You may cast the creature later from exile.)

Sea Hag

When Sea Hag enters, creatures your opponents control get -4/-0 until end of turn.

Sea Hag // Aquatic Ingress

Vantress Visions

Copy target activated or triggered ability you control. You may choose new targets for the copy.

Virtue of Knowledge

If a permanent entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Virtue of Knowledge // Vantress Visions

Lucky Clover

Whenever you cast an Adventure instant or sorcery spell, copy it. You may choose new targets for the copy.

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

Believe

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Look at the top card of your library. You may put it onto the battlefield if it's a creature card. If you don't, put it into your hand.

Reason

Reason // Believe

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.

Shield's Might

Target creature gets +2/+2 until end of turn. (Then exile this card. You may cast the creature later from exile.)

Garenbrig Carver

Garenbrig Carver // Shield's Might

Fight

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Target creature you control fights target creature an opponent controls.

Prepare

Untap target creature. It gets +2/+2 and gains lifelink until end of turn.

Prepare // Fight

Lupari Shield

Humans you control gain indestructible until your next turn. (Then exile this card. You may cast the creature later from exile.)

Karvanista, Loyal Lupari

Vigilance, trample, haste
Whenever Karvanista attacks, put a +1/+1 counter on each Human you control.

Karvanista, Loyal Lupari // Lupari Shield

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.")

Hauken's Insight

At the beginning of your upkeep, exile the top card of your library face down. You may look at that card for as long as it remains exiled.
Once during each of your turns, you may play a land or cast a spell from among the cards exiled with this permanent without paying its mana cost.

Jacob Hauken, Inspector

{T}: Draw a card, then exile a card from your hand face down. You may look at that card for as long as it remains exiled. You may pay {4}{U}{U}. If you do, transform Jacob Hauken, Inspector.

Jacob Hauken, Inspector // Hauken's Insight

Guard Change

Create a Monster Role token attached to target creature you control. (Enchanted creature gets +1/+1 and has trample.)

Ferocious Werefox

Ferocious Werefox // Guard Change

Temple of Mystery

Temple of Mystery enters tapped.
When Temple of Mystery enters, scry 1.
{T}: Add {G} or {U}.

Osgood, Operation Double

When you cast this spell, create a token that's a copy of it, except it isn't legendary.
{T}: Add {C}. Spend this mana only to cast an artifact spell or activate an ability of an artifact.
Paradox — Whenever you cast a spell from anywhere other than your hand, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Sword of the Ages

Sword of the Ages enters tapped.
{T}, Sacrifice Sword of the Ages and any number of creatures you control: Sword of the Ages deals X damage to any target, where X is the total power of the creatures sacrificed this way, then exile Sword of the Ages and those creature cards.

Temple of Cyclical Time

(Transforms from Ojer Pakpatiq, Deepest Epoch.)
{T}: Add {U}. Remove a time counter from Temple of Cyclical Time.
{2}{U}, {T}: Transform Temple of Cyclical Time. Activate only if it has no time counters on it and only as a sorcery.

Ojer Pakpatiq, Deepest Epoch

Flying
Whenever you cast an instant spell from your hand, it gains rebound. (Exile it as it resolves. At the beginning of your next upkeep, you may cast it from exile without paying its mana cost.)
When Ojer Pakpatiq dies, return it to the battlefield tapped and transformed under its owner's control with three time counters on it.

Ojer Pakpatiq, Deepest Epoch // Temple of Cyclical Time

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Alora, Merry Thief

Whenever you attack, up to one target attacking creature can't be blocked this turn. Return that creature to its owner's hand at the beginning of the next end step.
Choose a Background (You can have a Background as a second commander.)

Vega, the Watcher

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

Rabble Rousing

Hideaway 5 (When this enchantment enters, look at the top five cards of your library, exile one face down, then put the rest on the bottom in a random order.)
Whenever you attack with one or more creatures, create that many 1/1 green and white Citizen creature tokens. Then if you control ten or more creatures, you may play the exiled card without paying its mana cost.

Simic Growth Chamber

Simic Growth Chamber enters tapped.
When Simic Growth Chamber enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Lier, Disciple of the Drowned

Spells can't be countered.
Each instant and sorcery card in your graveyard has flashback. The flashback cost is equal to that card's mana cost.

Assimilation Aegis

When Assimilation Aegis enters, exile up to one target creature until Assimilation Aegis leaves the battlefield.
Whenever Assimilation Aegis becomes attached to a creature, for as long as Assimilation Aegis remains attached to it, that creature becomes a copy of a creature card exiled with Assimilation Aegis.
Equip {2}

Consider

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

Storyteller Pixie

Flying
Whenever you cast an Adventure spell, draw a card.

Halo Fountain

{W}, {T}, Untap a tapped creature you control: Create a 1/1 green and white Citizen creature token.
{W}{W}, {T}, Untap two tapped creatures you control: Draw a card.
{W}{W}{W}{W}{W}, {T}, Untap fifteen tapped creatures you control: You win the game.

Croaking Curse

Tap target creature. Create a Cursed Role token attached to it. (Enchanted creature is 1/1.)

Vantress Transmuter

Vantress Transmuter // Croaking Curse

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.)

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.

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."

Search for Tomorrow

Search your library for a basic land card, put it onto the battlefield, then shuffle.
Suspend 2—{G} (Rather than cast this card from your hand, you may pay {G} and exile it with two 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.)

Plains

Familiar's Ruse

As an additional cost to cast this spell, return a creature you control to its owner's hand.
Counter target spell.

Desperate Parry

Target creature gets -4/-0 until end of turn. (Then exile this card. You may cast the creature later from exile.)

Obyra's Attendants

Obyra's Attendants // Desperate Parry

Garenbrig Growth

Return target creature or land card from your graveyard to your hand. (Then exile this card. You may cast the enchantment later from exile.)

Virtue of Strength

If you tap a basic land for mana, it produces three times as much of that mana instead.

Virtue of Strength // Garenbrig Growth

Edgewall Inn

Edgewall Inn enters tapped.
As Edgewall Inn enters, choose a color.
{T}: Add one mana of the chosen color.
{3}, {T}, Sacrifice Edgewall Inn: Return target card that has an Adventure from your graveyard to your hand.

Mind

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Draw two cards.

Spring

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Spring // Mind

Graham O'Brien

Paradox — Whenever you cast a spell from anywhere other than your hand, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
Doctor's companion (You can have two commanders if the other is the Doctor.)

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Entry Denied

Return target creature you don't control with mana value 3 or less to its owner's hand. (Then exile this card. You may cast the creature later from exile.)

Beluna's Gatekeeper

Beluna's Gatekeeper // Entry Denied

Oaken Boon

Put two +1/+1 counters on target creature. (Then exile this card. You may cast the creature later from exile.)

Tuinvale Treefolk

Tuinvale Treefolk // Oaken Boon

Mend the Wilds

Put target permanent card from your graveyard on top of your library. (Then exile this card. You may cast the creature later from exile.)

Woodland Acolyte

When Woodland Acolyte enters, draw a card.

Woodland Acolyte // Mend the Wilds

Elven Chorus

You may look at the top card of your library any time.
You may cast creature spells from the top of your library.
Creatures you control have "{T}: Add one mana of any color."

Knacksaw Clique

Flying
{1}{U}, {Q}: Target opponent exiles the top card of their library. Until end of turn, you may play that card. ({Q} is the untap symbol.)

Glacial Fortress

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Petty Theft

Return target nonland permanent an opponent controls to its owner's hand.

Brazen Borrower

Flash
Flying
Brazen Borrower can block only creatures with flying.

Brazen Borrower // Petty Theft

Battlefield Thaumaturge

Each instant and sorcery spell you cast costs {1} less to cast for each creature it targets.
Heroic — Whenever you cast a spell that targets Battlefield Thaumaturge, Battlefield Thaumaturge gains hexproof until end of turn.

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.

Selesnya Sanctuary

Selesnya Sanctuary enters tapped.
When Selesnya Sanctuary enters, return a land you control to its owner's hand.
{T}: Add {G}{W}.

Sword of Forge and Frontier

Equipped creature gets +2/+2 and has protection from red and from green.
Whenever equipped creature deals combat damage to a player, exile the top two cards of your library. You may play those cards this turn. You may play an additional land this turn.
Equip {2}

Deserted Beach

Deserted Beach enters tapped unless you control two or more other lands.
{T}: Add {W} or {U}.

Eternal Witness

When Eternal Witness enters, you may return target card from your graveyard to your hand.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Rip the Seams

Destroy target tapped creature. (Then exile this card. You may cast the creature later from exile.)

Threadbind Clique

Threadbind Clique // Rip the Seams

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.)

Mindsplice Apparatus

Flash
At the beginning of your upkeep, put an oil counter on Mindsplice Apparatus.
Instant and sorcery spells you cast cost {1} less to cast for each oil counter on Mindsplice Apparatus.