The optimum single target DPS rotation is as follows, Starsurge on cooldown.
Start fight one cast pre-Lunar.
Starfall
Wrath once
Incarnation
Nature's Vigil (if you have it)
Sunfire, Moonfire
Starfall (when first Starfall duration ends)
Starfire until 0 energy
Celestial Alignment
Starfall (when second Starfall duration ends)
Moonfire (Sunfire will automatically be applied)
Starfire (utilize shooting stars procs)
Refresh Moonfire immediately before Celestial Alignment expires
Starfire to Solar Eclipse
Moonfire, Sunfire
Wrath until Lunar Eclipse.
Rinse and repeat (from the 'Starfall' below Celestial Alignment)