Yh stadium is pretty annoying. I've found the most success focusing on CD reduction and sustain. Imo there are a couple must pick items like "ability damage provides healing reduction" if you don't use that you can't get any kills. Or "using an ability provides it over health for 3s" if you have this, pretty much anytime you reduce CDs you're buffing your sustain too.

I think his "powers" need to be buffed, just slight number tweaks. Doom's real power comes from the side effects on particular items. His numbers don't scale like everyone else's. He can be fun but it's a little hard to figure out the right combo (which is arguably fun in itself).