UrTon is a magic Runeword created by combining a Ur Rune of Ritual and a Ton Rune of Invocation.
How to Create UrTon
You can create UrTon by adding the magic Ur Rune of Ritual and the magic Ton Rune of Invocation to a two-socketed Helm, Chest Armor, Pants, or Two-Handed Weapon.
Ur - Your Minion or Companion kills an enemy or dies. (10)
Ton - Invoke the Sorcerer's ites, dealing damage to enemies. (20)
Meteor
Overflow
UrTon can not overflow because the amount of Offering you receive from the Ur Rune exactly fills the required Offering of the Ton Rune.
Overflow occurs when your Ritual generates more Offering than required for the Invocation. The overflow effect is proportional to the amount Offering overflows.