Troll of Khazad-dûm

Troll of Khazad-dûm can't be blocked except by three or more creatures.
Swampcycling {1} ({1}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Village Rites

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards.

Animate Dead

Enchant creature card in a graveyard
When Animate Dead enters the battlefield, if it's on the battlefield, it loses "enchant creature card in a graveyard" and gains "enchant creature put onto the battlefield with Animate Dead." Return enchanted creature card to the battlefield under your control and attach Animate Dead to it. When Animate Dead leaves the battlefield, that creature's controller sacrifices it.
Enchanted creature gets -1/-0.

Demonic Tutor

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

Worn Powerstone

Worn Powerstone enters the battlefield tapped.
{T}: Add {C}{C}.

Helm of Awakening

Costly Plunder

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards.

Street Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Cycling—Pay 2 life. (Pay 2 life, Discard this card: Draw a card.)

Grim Tutor

Search your library for a card, put that card into your hand, then shuffle. You lose 3 life.

Boggart Bog

As Boggart Bog enters the battlefield, you may pay 3 life. If you don't, it enters the battlefield tapped.
{T}: Add {B}.

Boggart Trawler

When Boggart Trawler enters the battlefield, exile target player's graveyard.

Boggart Trawler // Boggart Bog

Sacrifice

As an additional cost to cast this spell, sacrifice a creature.
Add an amount of {B} equal to the sacrificed creature's mana value.

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Gloomfang Mauler

Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)
Backup 2 (When this creature enters the battlefield, put two +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.)
Menace

Injector Crocodile

When Injector Crocodile dies, incubate 3. (Create an Incubator token with three +1/+1 counters on it and "{2}: Transform this artifact." It transforms into a 0/0 Phyrexian artifact creature.)
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Rain of Filth

Until end of turn, lands you control gain "Sacrifice this land: Add {B}."

Soldevi Adnate

{T}, Sacrifice a black or artifact creature: Add an amount of {B} equal to the sacrificed creature's mana value.

Caged Sun

As Caged Sun enters the battlefield, choose a color.
Creatures you control of the chosen color get +1/+1.
Whenever a land's ability causes you to add one or more mana of the chosen color, add one additional mana of that color.

Reanimate

Put target creature card from a graveyard onto the battlefield under your control. You lose life equal to its mana value.

Twisted Abomination

{B}: Regenerate Twisted Abomination.
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Ultimate Price

Go for the Throat

Peer into the Abyss

Target player draws cards equal to half the number of cards in their library and loses half their life. Round up each time.

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Dark Ritual

Songs of the Damned

Add {B} for each creature card in your graveyard.

Jet Medallion

Black spells you cast cost {1} less to cast.

Night's Whisper

Corrupted Conviction

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Rampaging Spiketail

When Rampaging Spiketail enters the battlefield, target creature you control gets +2/+0 and gains indestructible until end of turn.
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Cabal Ritual

Add {B}{B}{B}.
Threshold — Add {B}{B}{B}{B}{B} instead if seven or more cards are in your graveyard.

Vampiric Tutor

Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Merciless Harlequin

Freerunning {1}{B} (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)
When Merciless Harlequin enters the battlefield, you draw a card and you lose 1 life.

Gauntlet of Power

As Gauntlet of Power enters the battlefield, choose a color.
Creatures of the chosen color get +1/+1.
Whenever a basic land is tapped for mana of the chosen color, its controller adds an additional one mana of that color.

Extraplanar Lens

Imprint — When Extraplanar Lens enters the battlefield, you may exile target land you control.
Whenever a land with the same name as the exiled card is tapped for mana, its controller adds one mana of any type that land produced.

Altar's Reap

Exhume

Each player puts a creature card from their graveyard onto the battlefield.

Burnished Hart

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Deadly Dispute

As an additional cost to cast this spell, sacrifice an artifact or creature.
Draw two cards and create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

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.

Hedron Crawler

{T}: Add {C}. ({C} represents colorless mana.)

Nasty End

As an additional cost to cast this spell, sacrifice a creature.
Draw two cards. If the sacrificed creature was legendary, draw three cards instead.

Phyrexian Tower

{T}: Add {C}.
{T}, Sacrifice a creature: Add {B}{B}.

Infernal Grasp

Destroy target creature. You lose 2 life.

Bubbling Muck

Until end of turn, whenever a player taps a Swamp for mana, that player adds an additional {B}.

Solemn Simulacrum

When Solemn Simulacrum enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Blackbloom Bog

Blackbloom Bog enters the battlefield tapped.
{T}: Add {B}.

Blackbloom Rogue

Menace (This creature can't be blocked except by two or more creatures.)
Blackbloom Rogue gets +3/+0 as long as an opponent has eight or more cards in their graveyard.

Blackbloom Rogue // Blackbloom Bog

Snow-Covered Swamp

Phyrexian Rager

When Phyrexian Rager enters the battlefield, you draw a card and you lose 1 life.

Culling the Weak

As an additional cost to cast this spell, sacrifice a creature.
Add {B}{B}{B}{B}.

Cabal Stronghold

{T}: Add {C}.
{3}, {T}: Add {B} for each basic Swamp you control.

Clattering Augur

Clattering Augur can't block.
When Clattering Augur enters the battlefield, you draw a card and you lose 1 life.
{2}{B}{B}: Return Clattering Augur from your graveyard to your hand.

Price of Fame

This spell costs {2} less to cast if it targets a legendary creature.
Destroy target creature.
Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Sol Ring

Horror of the Broken Lands

Whenever you cycle or discard another card, Horror of the Broken Lands gets +2/+1 until end of turn.
Cycling {B} ({B}, Discard this card: Draw a card.)

Skirge Familiar

Dark Petition

Search your library for a card, put that card into your hand, then shuffle.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, add {B}{B}{B}.

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.

Crypt Ghast

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever you tap a Swamp for mana, add an additional {B}.

Dusk Legion Zealot

When Dusk Legion Zealot enters the battlefield, you draw a card and you lose 1 life.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Bog Witch

Bitter Triumph

As an additional cost to cast this spell, discard a card or pay 3 life.
Destroy target creature or planeswalker.

Leaden Myr

Expedition Map

{2}, {T}, Sacrifice Expedition Map: Search your library for a land card, reveal it, put it into your hand, then shuffle.

Arcane Signet

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

Diabolic Intent

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a card, put that card into your hand, then shuffle.

Ornithopter of Paradise

Beseech the Mirror

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Search your library for a card, exile it face down, then shuffle. If this spell was bargained, you may cast the exiled card without paying its mana cost if that spell's mana value is 4 or less. Put the exiled card into your hand if it wasn't cast this way.

Lurching Rotbeast

Cycling {B} ({B}, Discard this card: Draw a card.)

Nykthos, Shrine to Nyx

{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)