Ornn nerf
I think they are just kneecapping him with this nerf. He is not strictly overpowered now. Has he seen pro play? I wouldnt be against the nerf if they gave him something to compensate. It is impossible to walk out of with just base ms so it would be a good nerf if he was overpowered.
If you play an immobile melee he is impossible to fight but farming at range and ignoring him you can go even with champs that outscale him. Becuase he doesn't have reliability like other tanks and is slow as hell. His lategame is bad for a tank because he has long cast times.
Orrn's badly designed because his Q is not dodgable without high movespeed/mobility and his cooldowns are so low there is never a window to stop sitting back like a pussy vs Ornn. They made him too slow.