Anduin is looking to follow his father into the nexus, and he won't let him down! In fact, no one's going down on his watch.
Anduin is a strong support that if left unchecked will pull his team through both damage and terrain, preventing isolation kills. While his trait makes him difficult for his enemies to deal with, proper timing of stuns will quickly render his support null. Unless he successfully juked, that is.
To be a good Anduin you'd need to anticipate where damage is going to land, predict when enemies will try to interrupt your casts, and position yourself safely so that you can pull your teammates out of danger should it be needed.
It would also completely nullify mainly Leorics tomb (50s CD), and Sonyas leap crater (70s CD), and to a lesser extent Tassadars walls. making those talents not completely useless against Anduin.
All things considered I think a 70s cd would be balanced, but that's just theorycrafting.
Thanks for you feedback :)