CemThul is a rare Runeword created by combining a Cem Rune of Ritual and a Thul Rune of Invocation.
How to Create CemThul
You can create CemThul by adding the magic Cem Rune of Ritual and the rare Thul Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Cem - Cast Evade. (75)
Thul - Invoke the Sorcerer's , inflicting Freeze and Vulnerable onto enemies. (400)
Mystical Frost Nova
Overflow
When CemThul overflows, you receive the Thul Rune's overflow effect (Up to 100% Increased Radius) 0.13 times.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.