Odylic Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
Whenever Odylic Wraith deals damage to a player, that player discards a card.

Font of Mythos

At the beginning of each player's draw step, that player draws two additional cards.

Filth

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
As long as Filth is in your graveyard and you control a Swamp, creatures you control have swampwalk.

Bog Wraith

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Lake of the Dead

If Lake of the Dead would enter, sacrifice a Swamp instead. If you do, put Lake of the Dead onto the battlefield. If you don't, put it into its owner's graveyard.
{T}: Add {B}.
{T}, Sacrifice a Swamp: Add {B}{B}{B}{B}.

Rackling

At the beginning of each opponent's upkeep, Rackling deals X damage to that player, where X is 3 minus the number of cards in their hand.

Tormented Soul

Tormented Soul can't block and can't be blocked.

Bog Raiders

Contaminated Ground

Enchant land
Enchanted land is a Swamp.
Whenever enchanted land becomes tapped, its controller loses 2 life.

Dark Ritual

Teferi's Puzzle Box

At the beginning of each player's draw step, that player puts the cards in their hand on the bottom of their library in any order, then draws that many cards.

Black Vise

As Black Vise enters, choose an opponent.
At the beginning of the chosen player's upkeep, Black Vise deals X damage to that player, where X is the number of cards in their hand minus 4.

Reassembling Skeleton

{1}{B}: Return Reassembling Skeleton from your graveyard to the battlefield tapped.

Underworld Dreams

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.

Nether Shadow

Haste
At the beginning of your upkeep, if Nether Shadow is in your graveyard with three or more creature cards above it, you may put Nether Shadow onto the battlefield.

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.

Evil Presence

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Drudge Skeletons

{B}: Regenerate Drudge Skeletons. (The next time this creature would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)

Blanket of Night

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

Spirit of the Night

Flying, trample, haste, protection from black
Spirit of the Night has first strike as long as it's attacking.

Insidious Dreams

As an additional cost to cast this spell, discard X cards.
Search your library for X cards, then shuffle and put those cards on top in any order.

Bone Dancer

Whenever Bone Dancer attacks and isn't blocked, you may put the top creature card of defending player's graveyard onto the battlefield under your control. If you do, Bone Dancer assigns no combat damage this turn.

Last Laugh

Whenever a permanent other than Last Laugh is put into a graveyard from the battlefield, Last Laugh deals 1 damage to each creature and each player.
When no creatures are on the battlefield, sacrifice Last Laugh.

Howling Mine

At the beginning of each player's draw step, if Howling Mine is untapped, that player draws an additional card.

Whispering Shade

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)
{B}: Whispering Shade gets +1/+1 until end of turn.

Hypnotic Specter

Flying
Whenever Hypnotic Specter deals damage to an opponent, that player discards a card at random.

Viseling

At the beginning of each opponent's upkeep, Viseling deals X damage to that player, where X is the number of cards in their hand minus 4.