CemXan is a legendary Runeword created by combining a Cem Rune of Ritual and a Xan Rune of Invocation.
How to Create CemXan
You can create CemXan by adding the magic Cem Rune of Ritual and the legendary Xan Rune of Invocation to a two-socketed Helm,
Chest Armor,
Pants, or
Two-Handed Weapon.


Overflow
CemXan can not overflow because the amount of Offering you receive from the Cem Rune exactly fills the required Offering of the Xan Rune.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.