Honestly, as good as Seer is, given that I solo farm 3/4 dungeons, I don't think I'd put her at the top of my list.
I think I'll agree with Aniri as the best void epic. I use her in Hydra, DTH, FW, Arena, and I've used her in CB.
As for Skimfos - I don't think he'd even make my top 50.
May I see your Seer? And which dungeons/stages does she do? Thanks!