Use 3rd skill first (Thunderclap), then the 1st skill (Storm call), then 4th skill (Ball lightning), then 1st skill (Stormcall) and then use your 2nd skill (Skyfire) and then 1st skill (Stormcall). Then If you are still low on HP use 1st skill, if not, use 3rd skill and repeat.
So it will be like: 3, 1, 4, 1, 2, 1, 1 or 3 and repeat.