Using a combo consisting of the spell explosion , and explosion potion and the spell energy bolt. This is an 8 step process it may seem like alot but it isnt very hard it just takes alot of practice.
Cast spell explosion.
Activate purple potion.
Hit escape. this removes the target from the purple potion.
Drop explosion spell on target.
Begin casting energy bolt.
Reactivate purple potion using last object.
Throw purple potion half way through the 2 second timer. May have to wait longer or less depending on your connection.
Drop energy bolt on target.