What is Ryze right now?

Seriously, i've been playing him pretty religiously lately and I haven't found success building him anything. i've built him Full AP, Mixed AP/Tank, and Full tank. What the literal fuck is Ryze now? I like his play-style (It's very similar to pre-rework) but either i'm playing him wrong and his skillcap is even higher than it was before, or he's waaaay too different and needs a role-assessment. I do like his new VO, Model and Effects, but it really feels like he has no teamfight presence anymore. He can farm really well but no matter how ahead he gets it feels like he has no teamfight presence...

And FYI I was REALLY good with Ryze pre-rework, like, I climbed to Plat playing him almost exclusively and loved his play-style.

I used to call him a teamfight, sustained-burst mage and grouped him with Karthus in that vane. I can't do that anymore because from what i've played he is awful at teamfights... Okay at duels, though.

Can anyone tell me how they've been having success playing Ryze?