The Nauglamir

At the beginning of each turn, if the Nauglamir
is equipped to a creature you control, add three
mana of any color.
Equipped creature can be attacked as if it was a
player or a planeswalker. Equip {3}
"Nauglamir, the Necklace of the Dwarves, most
renowned of their works in the Elder Days... was a carcanet of gold, and set therein were gems uncounted
from Valinor." - The Silmarillion