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.
Cem - Cast Evade. (75)
Xan - Your next Skill cast will be a guaranteed Critical Strike and Overpower. (800)
Overflow
CemXan can not overflow because the Xan Rune does not have an overflow effect.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.