CemTal is a magic Runeword created by combining a Cem Rune of Ritual and a Tal Rune of Invocation.
How to Create CemTal
You can create CemTal by adding the magic Cem Rune of Ritual and the magic Tal Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Cem - Cast Evade. (75)
Tal - Invoke the Spiritborn's Pestilent Swarm, dealing damage to enemies. (100)
Overflow
When CemTal overflows, you receive the Tal Rune's overflow effect (Increased Swarms Spawned) 0.5 times.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.