ZanXan is a legendary Runeword created by combining a Zan Rune of Ritual and a Xan Rune of Invocation.
How to Create ZanXan
You can create ZanXan by adding the magic Zan Rune of Ritual and the legendary Xan Rune of Invocation to a two-socketed 
Helm, 
Chest Armor, 
Pants, or 
Two-Handed Weapon.
Overflow
When ZanXan overflows, you receive the Xan Rune's overflow effect (Cast increases damage by 1% per 10 Offering) 0.07 times.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.
Legions
Helltide