Pandemonium Spark

Prerequisite: Eldritch Blast cantrip, Pact of the Flame feature

When you roll a 10 on the damage die for your eldritch blast, you can roll an additional d10 and add its damage to the total, rolling again if this die is also a 10, and so on. You can roll a total number of four damage dice for this damage roll, or eight damage dice on a critical hit.