After playing around with it for a little bit. It looks like the +2 lightning damage per intelligence for spark charges is not scaling correctly.
With 71 base damage from weapons, talents and the base damage of the ability. And 83 intelligence giving another 166. The damage on the tooltip only goes up from 2.3k to 4.4k. When 166 base damage should be atleast tripling the damage of the ability. (not including the small buff of base damage intelligence gives)