Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

Island

Frantic Search

Draw two cards, then discard two cards. Untap up to three lands.

Cavern Harpy

Flying
When Cavern Harpy enters, return a blue or black creature you control to its owner's hand.
Pay 1 life: Return Cavern Harpy to its owner's hand.

Asmodeus the Archfiend

Binding Contract — If you would draw a card, exile the top card of your library face down instead.
{B}{B}{B}: Draw seven cards.
{B}: Return all cards exiled with Asmodeus the Archfiend to their owner's hand and you lose that much life.

Torchling

{R}: Untap Torchling.
{R}: Target creature blocks Torchling this turn if able.
{R}: Change the target of target spell that targets only Torchling.
{1}: Torchling gets +1/-1 until end of turn.
{1}: Torchling gets -1/+1 until end of turn.

Aetherling

{U}: Exile Aetherling. Return it to the battlefield under its owner's control at the beginning of the next end step.
{U}: Aetherling can't be blocked this turn.
{1}: Aetherling gets +1/-1 until end of turn.
{1}: Aetherling gets -1/+1 until end of turn.

Command Tower

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

Fellwar Stone

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

Exotic Orchard

Essence Flux

Exile target creature you control, then return that card to the battlefield under its owner's control. If it's a Spirit, put a +1/+1 counter on it.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Rakdos Signet

Coveted Jewel

When Coveted Jewel enters, draw three cards.
{T}: Add three mana of any one color.
Whenever one or more creatures an opponent controls attack you and aren't blocked, that player draws three cards and gains control of Coveted Jewel. Untap it.

Quicksilver Elemental

{U}: Quicksilver Elemental gains all activated abilities of target creature until end of turn. (If any of the abilities use that creature's name, use this creature's name instead.)
You may spend blue mana as though it were mana of any color to pay the activation costs of Quicksilver Elemental's abilities.

Negate

Ghostly Flicker

Exile two target artifacts, creatures, and/or lands you control, then return those cards to the battlefield under your control.

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.)

Mairsil, the Pretender

When Mairsil, the Pretender enters, you may exile an artifact or creature card from your hand or graveyard and put a cage counter on it.
Mairsil, the Pretender has all activated abilities of all cards you own in exile with cage counters on them. You may activate each of those abilities only once each turn.

Horseshoe Crab

Spikeshot Elder

{1}{R}{R}: Spikeshot Elder deals damage equal to its power to any target.

Soliton

Mountain

Hateflayer

Wither (This deals damage to creatures in the form of -1/-1 counters.)
{2}{R}, {Q}: Hateflayer deals damage equal to its power to any target. ({Q} is the untap symbol.)

Crumbling Necropolis

Crumbling Necropolis enters tapped.
{T}: Add {U}, {B}, or {R}.

Cathartic Reunion

As an additional cost to cast this spell, discard two cards.
Draw three cards.

Blur

Exile target creature you control, then return that card to the battlefield under its owner's control.
Draw a card.

Candlekeep Sage

Commander creatures you own have "When this creature enters or leaves the battlefield, draw a card."

Dimir Signet

Amaranthine Wall

Defender
{2}: Amaranthine Wall gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Arcane Signet

Ovinomancer

When Ovinomancer enters, sacrifice it unless you return three basic lands you control to their owner's hand.
{T}, Return Ovinomancer to its owner's hand: Destroy target creature. It can't be regenerated. That creature's controller creates a 0/1 green Sheep creature token.

Izzet Signet

Buried Alive

Search your library for up to three creature cards, put them into your graveyard, then shuffle.

Final Parting

Search your library for two cards. Put one into your hand and the other into your graveyard. Then shuffle.

Oriq Loremage

{T}: Search your library for a card, put it into your graveyard, then shuffle. If it's an instant or sorcery card, put a +1/+1 counter on Oriq Loremage.

Skyship Stalker

Flying
{R}: Skyship Stalker gets +1/+0 until end of turn.
{R}: Skyship Stalker gains first strike until end of turn.
{R}: Skyship Stalker gains haste until end of turn.

Swamp

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.

Nevinyrral's Disk

Nevinyrral's Disk enters tapped.
{1}, {T}: Destroy all artifacts, creatures, and enchantments.

Gilded Lotus

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.