Thespian's Stage

{T}: Add {1} to your mana pool. {2}, {T}: Thespian's Stage becomes a copy of target land and gains this ability.

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.

Urborg, Tomb of Yawgmoth

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

Cloudpost

Cloudpost enters the battlefield tapped. {T}: Add {1} to your mana pool for each Locus on the battlefield.

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.

Glimmerpost

When Glimmerpost enters the battlefield, you gain 1 life for each Locus on the battlefield. {T}: Add {1} to your mana pool.

Vesuva

As Vesuva comes into play, you may choose a land in play. If you do, Vesuva comes into play tapped as a copy of the chosen land.

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.

Oblivion Sower

Ulamog, the Ceaseless Hunger

Basalt Monolith

Endbringer

Matter Reshaper

Thought-Knot Seer

Wastes

Ancient Tomb

Eye of Ugin

Walking Ballista

Sorcerous Spyglass

As Sorcerous Spyglass enters the battlefield, look at an opponent's hand, then choose any card name. Activated abilities of sources with the chosen name can't be activated unless they're mana abilities.