Snow-Covered Swamp

Smother

Destroy target creature with mana value 3 or less. It can't be regenerated.

Innocent Blood

Each player sacrifices a creature of their choice.

Skeletal Scrying

As an additional cost to cast this spell, exile X cards from your graveyard.
You draw X cards and you lose X life.

Cemetery Gate

Defender (This creature can't attack.)
Protection from black

Cabal Coffers

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

Engineered Plague

As this enchantment enters, choose a creature type.
All creatures of the chosen type get -1/-1.

Diabolic Edict

Target player sacrifices a creature of their choice.

Haunting Echoes

Exile all cards from target player's graveyard other than basic land cards. For each card exiled this way, search that player's library for all cards with the same name as that card and exile them. Then that player shuffles.

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Mind Sludge

Target player discards a card for each Swamp you control.

Planar Void

Whenever another card is put into a graveyard from anywhere, exile that card.

Nether Spirit

At the beginning of your upkeep, if this card is the only creature card in your graveyard, you may return this card to the battlefield.

Decree of Pain

Destroy all creatures. They can't be regenerated. Draw a card for each creature destroyed this way.
Cycling {3}{B}{B} ({3}{B}{B}, Discard this card: Draw a card.)
When you cycle this card, all creatures get -2/-2 until end of turn.

Duress

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Nevinyrral's Disk

This artifact enters tapped.
{1}, {T}: Destroy all artifacts, creatures, and enchantments.

Corrupt

Corrupt deals damage to any target equal to the number of Swamps you control. You gain life equal to the damage dealt this way.

Phyrexian Negator

Trample
Whenever this creature is dealt damage, sacrifice that many permanents.

Diabolic Tutor

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

Withering Wisps

At the beginning of the end step, if no creatures are on the battlefield, sacrifice this enchantment.
{B}: This enchantment deals 1 damage to each creature and each player. Activate no more times each turn than the number of snow Swamps you control.

Avatar of Woe

If there are ten or more creature cards total in all graveyards, this spell costs {6} less to cast.
Fear (This creature can't be blocked except by artifact creatures and/or black creatures.)
{T}: Destroy target creature. It can't be regenerated.

Eradicate

Exile target nonblack creature. Search its controller's graveyard, hand, and library for all cards with the same name as that creature and exile them. Then that player shuffles.