Deepwood Legate

If an opponent controls a Forest and you control a Swamp, you may cast this spell without paying its mana cost.
{B}: This creature gets +1/+1 until end of turn.

Homicidal Seclusion

As long as you control exactly one creature, that creature gets +3/+1 and has lifelink.

Peat Bog

This land enters tapped with two depletion counters on it.
{T}, Remove a depletion counter from this land: Add {B}{B}. If there are no depletion counters on this land, sacrifice it.

Boompile

{T}: Flip a coin. If you win the flip, destroy all nonland permanents.

Crystal Vein

{T}: Add {C}.
{T}, Sacrifice this land: Add {C}{C}.

Swamp

Demonlord Belzenlok

Flying, trample
When Demonlord Belzenlok enters, exile cards from the top of your library until you exile a nonland card, then put that card into your hand. If the card's mana value is 4 or greater, repeat this process. Demonlord Belzenlok deals 1 damage to you for each card put into your hand this way.

Subterranean Hangar

This land enters tapped.
{T}: Put a storage counter on this land.
{T}, Remove any number of storage counters from this land: Add {B} for each storage counter removed this way.

Beseech the Queen

({2/B} can be paid with any two mana or with {B}. This card's mana value is 6.)
Search your library for a card with mana value less than or equal to the number of lands you control, reveal it, put it into your hand, then shuffle.

Mastermind's Acquisition

Choose one —
• Search your library for a card, put it into your hand, then shuffle.
• Put a card you own from outside the game into your hand.

Nightmare Sower

Flying, lifelink
Whenever you cast a spell during an opponent's turn, put a -1/-1 counter on up to one target creature.

Skithiryx, the Blight Dragon

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{B}: Skithiryx gains haste until end of turn.
{B}{B}: Regenerate Skithiryx.

Bottomless Vault

This land enters tapped.
You may choose not to untap this land during your untap step.
At the beginning of your upkeep, if this land is tapped, put a storage counter on it.
{T}, Remove any number of storage counters from this land: Add {B} for each storage counter removed this way.

Gild

Exile target creature. Create a Gold token. (It's an artifact with "Sacrifice this token: Add one mana of any color.")

Dimir House Guard

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Sacrifice a creature: Regenerate this creature.
Transmute {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Stonespeaker Crystal

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Exile any number of target players' graveyards. Draw a card.

Makeshift Mannequin

Return target creature card from your graveyard to the battlefield with a mannequin counter on it. For as long as that creature has a mannequin counter on it, it has "When this creature becomes the target of a spell or ability, sacrifice it."

Cinderhaze Wretch

{T}: Target player discards a card. Activate only during your turn.
Put a -1/-1 counter on this creature: Untap this creature.

Dread Return

Return target creature card from your graveyard to the battlefield.
Flashback—Sacrifice three creatures. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Necrotic Ooze

As long as this creature is on the battlefield, it has all activated abilities of all creature cards in all graveyards.

Dross Golem

Affinity for Swamps (This spell costs {1} less to cast for each Swamp you control.)
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)

Hollow One

This spell costs {2} less to cast for each card you've cycled or discarded this turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Radiant Fountain

When this land enters, you gain 2 life.
{T}: Add {C}.

Phantasmagorian

When you cast this spell, any player may discard three cards. If a player does, counter Phantasmagorian.
Discard three cards: Return this card from your graveyard to your hand.

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Skirge Familiar

Dread

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
Whenever a creature deals damage to you, destroy it.
When Dread is put into a graveyard from anywhere, shuffle it into its owner's library.

Shriekmaw

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
When this creature enters, destroy target nonartifact, nonblack creature.
Evoke {1}{B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Sibsig Muckdraggers

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
When this creature enters, return target creature card from your graveyard to your hand.

Cackling Imp

Grim Poppet

This creature enters with three -1/-1 counters on it.
Remove a -1/-1 counter from this creature: Put a -1/-1 counter on another target creature.

Mage-Ring Network

{T}: Add {C}.
{1}, {T}: Put a storage counter on this land.
{T}, Remove any number of storage counters from this land: Add {C} for each storage counter removed this way.

Terrain Generator

{T}: Add {C}.
{2}, {T}: You may put a basic land card from your hand onto the battlefield tapped.

Geode Golem

Trample
Whenever this creature deals combat damage to a player, you may cast your commander from the command zone without paying its mana cost. (You still pay any additional costs.)

Thran Dynamo

Ebon Stronghold

This land enters tapped.
{T}: Add {B}.
{T}, Sacrifice this land: Add {B}{B}.

Massacre

If an opponent controls a Plains and you control a Swamp, you may cast this spell without paying its mana cost.
All creatures get -2/-2 until end of turn.