Fellwarstein

{T}: Erzeuge ein Mana einer beliebigen Farbe, das ein Land, das ein Gegner kontrolliert, produzieren könnte.

Nada acaba con una vida tranquila como unas riquezas recién descubiertas.

Piedra de Fellwar

{T}: Agrega un maná de cualquier color que pueda producir una tierra que controla un oponente.

Rien ne bouscule une vie tranquille aussi bien que l'acquisition de nouvelles richesses.

Pierre de Guermont

{T} : Ajoutez un mana de la couleur de votre choix qu'un terrain qu'un adversaire contrôle pourrait produire.

新たに見つかった富ほど平和な生活を砕くものもない。

友なる石

{T}：対戦相手がコントロールしている土地が生み出すことのできる色１色のマナ１点を加える。

新现财富，乃是平静生活的最大克星。

战野之石

{T}：加一点法术力，其颜色为由对手操控的地能产生之任一颜色。

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

"What do you have that I cannot obtain?"
—Mairsil, the Pretender

Duskmourn: House of Horror Commander

Bloomburrow Commander

Outlaws of Thunder Junction Commander

Murders at Karlov Manor Commander

Wilds of Eldraine Commander

It only produces one mana even if the land can produce more than one.

The ability can be activated if the opponent has no lands that produce mana, but the effect will not be able to generate any mana.

This works even if the opponent's lands are tapped. It only checks what kinds of mana can be produced, not if the abilities that produce them are usable right now.

Fellwar Stone checks the effects of all mana-producing abilities of lands your opponents control, but it doesn't check their costs. For example, Vivid Crag has the ability "{T}, Remove a charge counter from Vivid Crag: Add one mana of any color." If an opponent controls Vivid Crag and you control Fellwar Stone, you can tap Fellwar Stone for any color of mana. It doesn't matter whether Vivid Crag has a charge counter on it, and it doesn't matter whether it's untapped.

Fellwar Stone doesn't care about any restrictions or riders your opponents' lands (such as Ancient Ziggurat or Hall of the Bandit Lord) put on the mana they produce. It just cares about colors of mana.

The colors of mana are white, blue, black, red, and green. Fellwar Stone can't be tapped for colorless mana, even if a land an opponent controls could produce colorless mana.

When determining what colors of mana your opponents' lands could produce, take into account any applicable replacement effects that would apply to those lands' mana abilities (such as Contamination's effect, for example). If there is more than one, consider them in any possible order.