Ring of Thune is a uncommon Artifact — Equipment card from Magic 2013 (M13), collector number 213. Current market price: $0.33 (foil $1.79), TCGplayer market prices via Scryfall.
Equipped creature has vigilance. (Attacking doesn't cause it to tap.) At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's white. Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)