heatwave (t5 stun spell)Follow

Just wondering if anybody has noticed stun spells working any better if they are upgraded? The max level that can be stunned is no different from the app 1 then it is from the adept 1. I noticed the adept 1 does about 30 more damage, but when the mobs are 40+ that is not even something I care about in a stun spell (heck it could do 200 damage and still not make much difference)

Anyways does Stun spells stick better if they are upgraded, or is it really pointless to upgrade them? Most of the upgrades for the spell heatwave seem pretty high (8 gold and up) and I just don't see any reason to upgrade it.