Crackling Cloud
Creates a cloud of craclkling electrical energy, dealing 2d4 (2-8) Electrical Damage per 2 Caster Levels (max 16d4 -16-64) every 2 seconds for 8 seconds to all targets within the cloud. Reflex Save for half upon entering, no save for tagets remaining in the cloud.
When this spell ends, it expends its remaining energy in a massive Electrical discharge, targets within the cloud when this happens must make a Fortitude Save or be stunned for 3d4 (3-12) seconds
[Edit: after considering a few things i changed a few details of the spell, while still retaining the core idea behind it]