Gauntlet of Power TSP-255/5075 (The List Reprints)

As this artifact enters, choose a color. Creatures of the chosen color get +1/+1. Whenever a basic land is tapped for mana of the chosen color, its controller adds an additional one mana of that color.

NM - $9.50
LP - $7.50
MP - $5.50
HP - $4.00
DMG - $2.00