凶兆の廃墟

凶兆の廃墟が戦場に出るに際し、あなたの手札にあり沼や山であるカード１枚を公開してもよい。そうしないなら、凶兆の廃墟はタップ状態で戦場に出る。
{T}：{B}か{R}を加える。

Foreboding Ruins

As Foreboding Ruins enters, you may reveal a Swamp or Mountain card from your hand. If you don't, Foreboding Ruins enters tapped.
{T}: Add {B} or {R}.

Duskmourn: House of Horror Commander

The Lost Caverns of Ixalan Commander

As Foreboding Ruins enters the battlefield, you may reveal a Swamp or Mountain card from your hand. If you don't, Foreboding Ruins enters the battlefield tapped.
{T}: Add {B} or {R}.

Doctor Who

If a Swamp or Mountain is entering the battlefield from your hand at the same time as Forboding Ruins, you may reveal the other land to have Forboding Ruins enter untapped.

If an effect instructs you to put Forboding Ruins onto the battlefield tapped, it will still enter the battlefield tapped even if you reveal a land card from your hand.

Lands don't have a subtype just because they can produce mana of the corresponding color. Forboding Ruins itself is neither a Swamp nor a Mountain, even though it produces black and red mana, so you can't reveal one to satisfy the ability of another.

You may reveal any land card with either or both of the appropriate subtypes. It doesn't have to be a basic land. For example, you could reveal Sunken Hollow from the Battle for Zendikar set to satisfy the ability of Forboding Ruins.