Maze of Shadows

{T}: Add {C}.
{T}: Untap target attacking creature with shadow. Prevent all combat damage that would be dealt to and dealt by that creature this turn.

Dauthi Cutthroat

Shadow (This creature can block or be blocked by only creatures with shadow.)
{1}{B}, {T}: Destroy target creature with shadow.

Dauthi Ghoul

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever a creature with shadow dies, put a +1/+1 counter on Dauthi Ghoul.

Nether Traitor

Haste
Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever another creature is put into your graveyard from the battlefield, you may pay {B}. If you do, return Nether Traitor from your graveyard to the battlefield.

Swamp

Stronghold Overseer

Flying
Shadow (This creature can block or be blocked by only creatures with shadow.)
{B}{B}: Creatures with shadow get +1/+0 until end of turn and creatures without shadow get -1/-0 until end of turn.

Umbris, Fear Manifest

Umbris, Fear Manifest gets +1/+1 for each card your opponents own in exile.
Whenever Umbris or another Nightmare or Horror you control enters, target opponent exiles cards from the top of their library until they exile a land card.

Gravestorm

At the beginning of your upkeep, target opponent may exile a card from their graveyard. If that player doesn't, you may draw a card.

Dauthi Voidwalker

Shadow (This creature can block or be blocked by only creatures with shadow.)
If a card would be put into an opponent's graveyard from anywhere, instead exile it with a void counter on it.
{T}, Sacrifice Dauthi Voidwalker: Choose an exiled card an opponent owns with a void counter on it. You may play it this turn without paying its mana cost.

Darkness

Prevent all combat damage that would be dealt this turn.

Island

Shadow Rift

Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)
Draw a card.

Dauthi Trapper

{T}: Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)

Thalakos Deceiver

Shadow (This creature can block or be blocked by only creatures with shadow.)
Whenever Thalakos Deceiver attacks and isn't blocked, you may sacrifice it. If you do, gain control of target creature. (This effect lasts indefinitely.)

Go for the Throat

Dauthi Warlord

Shadow (This creature can block or be blocked by only creatures with shadow.)
Dauthi Warlord's power is equal to the number of creatures on the battlefield with shadow.

Dauthi Embrace

{B}{B}: Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)

Dark Ritual

Vashta Nerada

Indestructible
Shadow (This creature can block or be blocked by only creatures with shadow.)
Morbid — At the beginning of each end step, if a creature died this turn, put a +1/+1 counter on Vashta Nerada.

Thalakos Dreamsower

Shadow (This creature can block or be blocked by only creatures with shadow.)
You may choose not to untap Thalakos Dreamsower during your untap step.
Whenever Thalakos Dreamsower deals damage to an opponent, tap target creature. That creature doesn't untap during its controller's untap step for as long as Thalakos Dreamsower remains tapped.

Fallen Shinobi

Ninjutsu {2}{U}{B} ({2}{U}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Whenever Fallen Shinobi deals combat damage to a player, that player exiles the top two cards of their library. Until end of turn, you may play those cards without paying their mana costs.