Nocturne Spell Shield, Nasus Q
Long story short, Nocturne's W does not block the damage of, nor does it activate off of being hit by Nasus's Q. I'm not entirely sure if this is a bug or if it is supposed to be there, but if I'm being honest if RIOT ever wants Nocturne to be competitive I think fixing this is a key component.
Thanks for Your time. I will be linking to another post I am about to write shortly which will contain my ideas on how to fix Nocturne and make him more competitive.