CemRandom Rare or Legendary Rune is a rare Runeword created by combining a Cem Rune of Ritual and a Random Rare or Legendary Rune Rune of Invocation.
How to Create CemRandom Rare or Legendary Rune
You can create CemRandom Rare or Legendary Rune by adding the magic Cem Rune of Ritual and the rare Random Rare or Legendary Rune Rune of Invocation to a two-socketed Helm,
Chest Armor,
Pants, or
Two-Handed Weapon.


Overflow
CemRandom Rare or Legendary Rune can not overflow because the Random Rare or Legendary Rune 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.