Thunder 2 (time on tank pull)

Opening rotation: Fire 3 > Raging Strikes > Fire 1 (4-5) > Swiftcast > Flare > Convert > Fire 1 > Blizzard 3 > Thunder 1 > Blizzard 1 (if MP Tick RNG isn't kind)
Normal rotation: Fire 3 > Fire 1 (4-5) > Blizzard 3 > Thunder 1 (blizzard 1 if required) and repeat.

I wouldn't spam Flare like that for single targets at all.