Cavern of Souls

As Cavern of Souls enters the battlefield, choose a creature type. {T}: Add {1} to your mana pool. {T}: Add one mana of any color to your mana pool. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.

City of Traitors

If you play any land, sacrifice City of Traitors. {T}: Add two colorless mana to your mana pool.

Thorn of Amethyst

Noncreature spells cost {1} more to play.

Chalice of the Void

Chalice of the Void enters the battlefield with X charge counters on it. Whenever a player casts a spell with converted mana cost equal to the number of charge counters on Chalice of the Void, counter that spell.

Simian Spirit Guide

Remove Simian Spirit Guide in your hand from the game: Add {R} to your mana pool.

Urborg, Tomb of Yawgmoth

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

Umezawa's Jitte

Whenever equipped creature deals combat damage, put two charge counters on Umezawa's Jitte. Remove a charge counter from Umezawa's Jitte: Choose one — Equipped creature gets +2/+2 until end of turn; or target creature gets -1/-1 until end of turn; or you gain 2 life. Equip {2}

Eldrazi Temple

{T}: Add {1} to your mana pool. {T}: Add {2} to your mana pool. Spend this mana only to cast colorless Eldrazi spells or activate abilities of colorless Eldrazi.

Grim Monolith

Grim Monolith does not untap during your untap phase. {4}: Untap Grim Monolith. {T}: Add three colorless mana to your mana pool. Play this ability as a mana source.

Endless One

Oblivion Sower

Ulamog, the Ceaseless Hunger

Eldrazi Mimic

Endbringer

Matter Reshaper

Reality Smasher

Thought-Knot Seer

Wastes

Ancient Tomb

Eye of Ugin

Wasteland