Wheel of Elements
The Wheel of Elements is an artifact. Its quality varies from uncommon to mythic with its rank.
It can be found in the [Trove of Elemental Evil].
Some information regarding this item is clarified in this post by a game designer on the official forums
Fire — Deal 5% bonus Damage as fire for 14/18/22/26/30 seconds.
Wind — Grants control immunity and increased Movement Speed for 2/3/4/5/6 seconds.
Earth — Grant 20/40/60/80/100% of Maximum Hit Points as Temporary Hit Points for 5 seconds.
Water — Heal for 26/32/38/44/50% of Maximum Hit Points over 30 seconds.