Concept for a changed Singed Ult

I don't have time to develop the idea properly right now, but the basics is that Singed's ult could be an AoE version of his E, basing the size and duration on his % remaining mana. (To reflect how much he's been using his E Q.) Effectively, I was imagining what would he do if, instead of running around with his poison, he just wanted to create a completely toxic environment, akin to gas bombing.

~CrimsonCobra3