I tried it. You can alternate it, but its very low overall dps, and not many targets would be susceptible to it outside of a 1v1 with overconfident dps. CCs you think it would be great for, but they still can kite you. LoS is still an issue. Its not going to win you a fight in many situations. On the dummies on top of the ship, fire-bliz brings them to 0 health in 10 gcd or so, fire-fire IV in 5.