Ring of Thune is a uncommon Artifact — Equipment card from Commander Legends (CMR), collector number 468. Current market price: $0.18, 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.)