Gauntlet of Might

Artifact, 4 (4)
Red creatures get +1/+1.

Whenever a Mountain is tapped for mana, its controller adds {R} to his or her mana pool (in addition to the mana the land produces).¹
Illus. Christopher Rush

Gatherer Card Rulings [Nov 2009]

• 10/4/2004: Dual lands which have Mountain as one of their types produce an extra red mana when tapped for either color.

Format Legality	Legal in Vintage, Legacy Banned in Extended, Standard, MTGO Classic
Printings (3/3)	Unlimited Edition (Rare) Limited Edition Beta (Rare) Limited Edition Alpha (Rare)