Urborg, Tomb of Yawgmoth

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

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Archfiend of Despair

Flying
Your opponents can't gain life.
At the beginning of each end step, each opponent loses life equal to the life that player lost this turn. (Damage causes loss of life.)

Bojuka Bog

Bojuka Bog enters the battlefield tapped.
When Bojuka Bog enters the battlefield, exile target player's graveyard.
{T}: Add {B}.

Reaper from the Abyss

Flying
Morbid — At the beginning of each end step, if a creature died this turn, destroy target non-Demon creature.

Athreos, God of Passage

Indestructible
As long as your devotion to white and black is less than seven, Athreos isn't a creature.
Whenever another creature you own dies, return it to your hand unless target opponent pays 3 life.

Lord of the Void

Flying
Whenever Lord of the Void deals combat damage to a player, exile the top seven cards of that player's library, then put a creature card from among them onto the battlefield under your control.

Rune-Scarred Demon

Flying
When Rune-Scarred Demon enters the battlefield, search your library for a card, put it into your hand, then shuffle.

Xathrid Necromancer

Whenever Xathrid Necromancer or another Human creature you control dies, create a tapped 2/2 black Zombie creature token.

Fetid Heath

{T}: Add {C}.
{W/B}, {T}: Add {W}{W}, {W}{B}, or {B}{B}.

Edgewalker

Cleric spells you cast cost {W}{B} less to cast. This effect reduces only the amount of colored mana you pay. (For example, if you cast a Cleric spell with mana cost {1}{W}, it costs {1} to cast.)

Drifting Meadow

Drifting Meadow enters the battlefield tapped.
{T}: Add {W}.
Cycling {2} ({2}, Discard this card: Draw a card.)

Mentor of the Meek

Whenever another creature with power 2 or less enters the battlefield under your control, you may pay {1}. If you do, draw a card.

Temple of Silence

Temple of Silence enters the battlefield tapped.
When Temple of Silence enters the battlefield, scry 1.
{T}: Add {W} or {B}.

Swamp

Tainted Field

{T}: Add {C}.
{T}: Add {W} or {B}. Activate only if you control a Swamp.

Eater of Hope

Flying
{B}, Sacrifice another creature: Regenerate Eater of Hope.
{2}{B}, Sacrifice two other creatures: Destroy target creature.

Isolated Chapel

Isolated Chapel enters the battlefield tapped unless you control a Plains or a Swamp.
{T}: Add {W} or {B}.

Razaketh, the Foulblooded

Flying, trample
Pay 2 life, Sacrifice another creature: Search your library for a card, put that card into your hand, then shuffle.

Dawn

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Return all creature cards with power 2 or less from your graveyard to your hand.

Dusk

Destroy all creatures with power 3 or greater.

Dusk // Dawn

Shadowborn Apostle

A deck can have any number of cards named Shadowborn Apostle.
{B}, Sacrifice six creatures named Shadowborn Apostle: Search your library for a Demon creature card, put it onto the battlefield, then shuffle.

Immortal Servitude

Return each creature card with mana value X from your graveyard to the battlefield.

Ob Nixilis, Unshackled

Flying, trample
Whenever an opponent searches their library, that player sacrifices a creature and loses 10 life.
Whenever another creature dies, put a +1/+1 counter on Ob Nixilis, Unshackled.

Black Market

Whenever a creature dies, put a charge counter on Black Market.
At the beginning of your precombat main phase, add {B} for each charge counter on Black Market.

Desecration Demon

Flying
At the beginning of each combat, any opponent may sacrifice a creature. If a player does, tap Desecration Demon and put a +1/+1 counter on it.

Crypt of Agadeem

Crypt of Agadeem enters the battlefield tapped.
{T}: Add {B}.
{2}, {T}: Add {B} for each black creature card in your graveyard.

Plains

Barren Moor

Barren Moor enters the battlefield tapped.
{T}: Add {B}.
Cycling {B} ({B}, Discard this card: Draw a card.)

Shadowborn Demon

Flying
When Shadowborn Demon enters the battlefield, destroy target non-Demon creature.
At the beginning of your upkeep, if there are fewer than six creature cards in your graveyard, sacrifice a creature.

Concealed Courtyard

Concealed Courtyard enters the battlefield tapped unless you control two or fewer other lands.
{T}: Add {W} or {B}.

Ormendahl, Profane Prince

Westvale Abbey

{T}: Add {C}.
{5}, {T}, Pay 1 life: Create a 1/1 white and black Human Cleric creature token.
{5}, {T}, Sacrifice five creatures: Transform Westvale Abbey, then untap it.

Westvale Abbey // Ormendahl, Profane Prince

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters the battlefield, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Angel of Glory's Rise

Flying
When Angel of Glory's Rise enters the battlefield, exile all Zombies, then return all Human creature cards from your graveyard to the battlefield.

Harvester of Souls

Deathtouch
Whenever another nontoken creature dies, you may draw a card.

Command Tower

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

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.)

Liliana's Contract

When Liliana's Contract enters the battlefield, you draw four cards and you lose 4 life.
At the beginning of your upkeep, if you control four or more Demons with different names, you win the game.

Ghost Quarter

{T}: Add {C}.
{T}, Sacrifice Ghost Quarter: Destroy target land. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

Demon of Death's Gate

You may pay 6 life and sacrifice three black creatures rather than pay this spell's mana cost.
Flying, trample

Caves of Koilos

{T}: Add {C}.
{T}: Add {W} or {B}. Caves of Koilos deals 1 damage to you.

Skirsdag High Priest

Morbid — {T}, Tap two untapped creatures you control: Create a 5/5 black Demon creature token with flying. Activate only if a creature died this turn.

Return to the Ranks

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Return X target creature cards with mana value 2 or less from your graveyard to the battlefield.

Thrumming Stone

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your library.)

Flagstones of Trokair

{T}: Add {W}.
When Flagstones of Trokair is put into a graveyard from the battlefield, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle.

Ashnod's Altar

Polluted Mire

Polluted Mire enters the battlefield tapped.
{T}: Add {B}.
Cycling {2} ({2}, Discard this card: Draw a card.)