Plague Nova trash or just me?

I do nothing but poison damage but it takes half a map clear to get my Plague Nova to 1005 then I get one use out of it. I am only level 14 but seems like it should be at least somewhat more useful.

Is there some benefit of this skill that I am missing?

Late game you can spam it at 100% after firing just 1 gas arrow. Prio AOE and + skill gem level supports.