I do not feel like doing maths and I am not a pro Ninja player. However, I did want to point out Hollow Nozuchi, which some posters seem to be forgetting. I can easily imagine a situation during an add phase where you can use Doton on the single target boss, then turn your attention to the incoming adds and burst them down with Katon and your AoE combo, triggering extra damage on the boss everytime. But that seems like a very specialized moment.