Ofc we dont know exactly how he is to play yet but I cant imagine him being bad with the sheer amount of options he brings.
%HP damage, zone control+wave clear, long range execute, aoe shielding, aoe speed boost in a pretty big area, mana sustain (not sure how relevant that is), several options of cc depending on situation and a potentially huge crowd control ultimate that absolutely screws a ton of champions.
Obviously it comes down to how the champion is tuned but once players get good with him and pros have some time on him I cant imagine him being bad. Worst case scenario he ends up being a “pro only” champion like aphelios. Huge skill ceiling but when used by pros becomes so stupid he has to be nerfed into oblivion
He is so versatile that he will inevitably end up being balanced for support, at which point he might indeed become proplay staple.
With utility he brings, I can’t see him being balanced for midlane without being overpowered as a support, but we will see, maybe he will have insane AP ratios.
I don’t think skill ceiling will be that huge. You have 10 abilities, yes, but all of them are rather straightforward.