I'm gonna say primarily jungle, then mid and possibly even support.
Jungle should be obvius, free damage without mana costs and a AoE stun if you need it, he can gank from a huge distance no matter the terrain and can come in with a huge area stun and extra CC once he hits level 6.
Mid will work for kinda the same reasons, while I don't know how easy he will play in lane and how his trades will go you have the potential to out sustain your opponent at least in mana costs. And your roams will be amazing.
I can also see him working as a support but it'll be tricky (or not work at all), he has the CC for it and might be able to zone like crazy, just gotta watch out about pushing lane or messing up the CS of your ADC. Would work as a roaming support though, you'll get around easy enough.
Hell, he might even work top, not like you have to waste mana to work on their big HP bars. I am worried about champions with gap closers though so top will be really dependent on who your facing.