I think I've said this before and if you've already seen it, sorry for the repetition, but honestly I think they should've added AoE slowspells in the form of Verblizzard and Verwater, where the mana generated from each scales up with how many targets you hit with them. I like your idea, but, personally, I think thematically it doesn't fit with the RDM "Build up, dart in, burst down, flip out" pattern.