XolThul is a legendary Runeword created by combining a Xol Rune of Ritual and a Thul Rune of Invocation.
How to Create XolThul
You can create XolThul by adding the legendary Xol Rune of Ritual and the rare Thul Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Xol - Invoke a Skill from another Class. (150)
Thul - Invoke the Sorcerer's , inflicting Freeze and Vulnerable onto enemies. (400)
Mystical Frost Nova
Overflow
When XolThul 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.