First of all, I agree that it's useless sadly and should be reworked, plus the animation is actually quite good (I like ice spikes lol).

BUT, you can't possibly put a damage buffer or resistance down for any type of damage on it because it would be mandatory to use it every 20sec when not in need of Suiton, making fuma and raiton useless. Aggro management is already great, so also no need there.
You also have to think of it's rework with Ten Chi Jin, since you can fuma-hyoton-doton with the rigth inputs, so it needs to have some effect other than potency. What it could do however is having no potency but applying a DoT with a very long duration like 60 sec so other single target ninjutsu are not useless, with reasonnable tics, maybe not quite as strong a the Samurai one, but still something along that line. Maybe 20/tics for 60 sec, making it 600 potency total. It would benefit from TCJ, and be worth cliping GCD once for a DoT damage. You can say it's a frostburn if you want to have a reason for justifying it ^^.

I'd like to see some DoT again since we don't have mutilate anymore. It was great to have some other source of non combo damage.