Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. This land deals 1 damage to you.

Island

Kolaghan's Command

Choose two —
• Return target creature card from your graveyard to your hand.
• Target player discards a card.
• Destroy target artifact.
• Kolaghan's Command deals 2 damage to any target.

Clutch of the Undercity

Return target permanent to its owner's hand. Its controller loses 3 life.
Transmute {1}{U}{B} ({1}{U}{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.)

Tainted Peak

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

Tainted Isle

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

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Thrull Parasite

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
{T}, Pay 2 life: Remove a counter from target nonland permanent.

Skyclave Relic

Kicker {3}
Indestructible
When this artifact enters, if it was kicked, create two tapped tokens that are copies of this artifact.
{T}: Add one mana of any color.

Unnatural Selection

{1}: Choose a creature type other than Wall. Target creature becomes that type until end of turn.

Rakdos Ickspitter

{T}: This creature deals 1 damage to target creature and that creature's controller loses 1 life.

Swamp

Tevesh Szat, Doom of Fools

+2: Create two 0/1 black Thrull creature tokens.
+1: You may sacrifice another creature or planeswalker. If you do, draw two cards, then draw another card if the sacrificed permanent was a commander.
−10: Gain control of all commanders. Put all commanders from the command zone onto the battlefield under your control.
Tevesh Szat, Doom of Fools can be your commander.
Partner

Engineered Plague

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

Underground Sea

Countersquall

Counter target noncreature spell. Its controller loses 2 life.

Reflecting Pool

{T}: Add one mana of any type that a land you control could produce.

Badlands

Endrek Sahr, Master Breeder

Whenever you cast a creature spell, create X 1/1 black Thrull creature tokens, where X is that spell's mana value.
When you control seven or more Thrulls, sacrifice Endrek Sahr.

Thrull Champion

Thrull creatures get +1/+1.
{T}: Gain control of target Thrull for as long as you control this creature.

Urborg

{T}: Add {B}.
{T}: Target creature loses first strike or swampwalk until end of turn.

Undercover Operative

You may have this creature enter as a copy of any creature on the battlefield, except it enters with a shield counter on it if you control that creature. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)

Demonic Tutor

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

Sol Ring

Undermine

Counter target spell. Its controller loses 3 life.

Kaervek the Merciless

Whenever an opponent casts a spell, Kaervek deals damage equal to that spell's mana value to any target.