Ob Nixilis, the Fallen

Landfall — Whenever a land you control enters, you may have target player lose 3 life. If you do, put three +1/+1 counters on Ob Nixilis, the Fallen.

Wave of Terror

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
At the beginning of your draw step, destroy each creature with mana value equal to the number of age counters on Wave of Terror. They can't be regenerated.

Western Paladin

{B}{B}, {T}: Destroy target white creature.

Wall of Shadows

Defender (This creature can't attack.)
Prevent all damage that would be dealt to Wall of Shadows by creatures it's blocking.
Wall of Shadows can't be the target of spells that can target only Walls or of abilities that can target only Walls.

Arcane Signet

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

Swamp

Soul Exchange

As an additional cost to cast this spell, exile a creature you control.
Return target creature card from your graveyard to the battlefield. Put a +2/+2 counter on that creature if the exiled creature was a Thrull.

Uncle Istvan

Prevent all damage that would be dealt to Uncle Istvan by creatures.

Eastern Paladin

{B}{B}, {T}: Destroy target green creature.

Brainspoil

Destroy target creature that isn't enchanted. It can't be regenerated.
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.)

Plaguecrafter

When Plaguecrafter enters, each player sacrifices a creature or planeswalker. Each player who can't discards a card.

Simulacrum

You gain life equal to the damage dealt to you this turn. Simulacrum deals damage to target creature you control equal to the damage dealt to you this turn.

Command Tower

Stromgald Cabal

{T}, Pay 1 life: Counter target white spell.

Golos, Tireless Pilgrim

When Golos, Tireless Pilgrim enters, you may search your library for a land card, put that card onto the battlefield tapped, then shuffle.
{2}{W}{U}{B}{R}{G}: Exile the top three cards of your library. You may play them this turn without paying their mana costs.

Chromatic Lantern

Lands you control have "{T}: Add one mana of any color."
{T}: Add one mana of any color.

Infernal Darkness

Cumulative upkeep—Pay {B} and 1 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
If a land is tapped for mana, it produces {B} instead of any other type.

Deathgrip

Drudge Spell

{B}, Exile two creature cards from your graveyard: Create a 1/1 black Skeleton creature token. It has "{B}: Regenerate this creature."
When Drudge Spell leaves the battlefield, destroy all Skeleton tokens. They can't be regenerated.

Worms of the Earth

Players can't play lands.
Lands can't enter the battlefield.
At the beginning of each upkeep, any player may sacrifice two lands or have Worms of the Earth deal 5 damage to that player. If a player does either, destroy Worms of the Earth.

Ankh of Mishra

Whenever a land enters, Ankh of Mishra deals 2 damage to that land's controller.

Bojuka Bog

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

Polluted Bonds

Whenever a land an opponent controls enters, that player loses 2 life and you gain 2 life.

Hecatomb

When Hecatomb enters, sacrifice Hecatomb unless you sacrifice four creatures.
Tap an untapped Swamp you control: Hecatomb deals 1 damage to any target.

Gray Merchant of Asphodel

When Gray Merchant of Asphodel enters, 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.)

Massacre Wurm

When Massacre Wurm enters, creatures your opponents control get -2/-2 until end of turn.
Whenever a creature an opponent controls dies, that player loses 2 life.

Storm Cauldron

Each player may play an additional land during each of their turns.
Whenever a land is tapped for mana, return it to its owner's hand.

Paralyze

Enchant creature
When Paralyze enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.
At the beginning of the upkeep of enchanted creature's controller, that player may pay {4}. If the player does, untap the creature.