Before i begin, i am a Noc main, and have been playing him since Season 3. I have 438k mastery points on him.
The Q change would be quite nice, but what are we willing to take away to grant that. Keeping Noc as he is currently and giving that buff would make him quite strong. I think his Q is already a pretty strong ability with the damage it does, the damage buff it gives, and the movement speed. His Q already allows him to escape from champs quite easily. I don't believe you need to allow him to ignore terrain. If I were to buff his Q in any way, i would remove the cast time. This would allow him to escape champs with greater ease, and wouldn't stop his auto attacks to use the ability.
I understand how allowing his Q to ignore terrain would make ganks easier for him, but his early ganks are nowhere as bad as some champs who require ult to gank such as
and
. If you tell your laners to allow their lane opponent to push the lane so you can gank, you can easily secure a kill or a flash.
At a glance, looking at Nocturne's kit may reveal to some that his kit is very simple. But there are lots of neat tricks in his kit which only dedicated mains will know. Simply put, his kit is far from simple. I'd say his W is the ability which requires the most mastery to use. A good Noc main will be able to gauge the abilities of other opponents and properly block them. A sub par or new Noc player will most likely waste away his W, or block something that wouldn't have done much to begin with. Although buffing his W as you said would be great, it would make it pretty difficult to peel him away. You would need champs with abilities, such as Tahm's eating ability, who can save Noc's target from dying. With the current W, it is pretty easy to push Noc away from his target, and a good Noc main will realize this, and use his W appropriately, or rely on his team to engage and distract the enemy from the carry.
Some seasons ago Riot gave Fidd and Noc movement speed toward feared champs. Along with this they changed how fear works. Instead of a feared unit moving around in random directions, they made the feared unit run away from the champ who feared it. This, to be quite honest, was a good buff to Nocturne. It allowed him to direct his target to a specific area. The movement speed toward the feared champ also gave him a good buff, allowing him to make his way around the feared unit and direct the unit in any way he pleases. A good Noc main will use this to their advantage and will turn around a feared champ who is trying to run away and direct him to his team, away from turret range, etc.
I like the idea of double healing from Noc's passive on feared champs. That is definitely a buff i would like to see. The damage increase from basic attacks may become a bit overpowered since Noc's fear is already a pretty strong ability. I think it's the second longest fear in the game behind
. Maybe double healing and damage from passive on feared champs. That could work. It would allow attack speed builds to become a bit stronger that what they are now.
I like the R changes you have in mind, and I think it would be a good addition to his ult. Nocturne is a nightmare after all, so him knowing where low health champs who fear a Noc ult would make sense thematically. Maybe to not make the ult too overpowered, allow him to have vision like you are proposing, but keep the range the same. To be honest though, I would like to see a range increase and a lower cooldown.
You didn't mention anything about his passive. What i would recommend is to add an AD scaling on his passive. That would help quite a bit in the jungle.
Overall, I think Nocturne is in a good position, and buffing him too much would make him too strong. I would consider him quite strong in fact, the only reason he is not trouble is because no one plays him and he falls off. If you really want to realize how strong Nocturne is, play him in mid lane or top lane, where his abilities are more relevant to champs. At level 3, it is very easy to get first blood.
Tl;Dr
All the buffs mentioned above may be overkill. Some buffs i would like to see are adding an AD scaling on his passive. Remove cast time on his Q. Keep his W as it currently is. Maybe increase the damage from passive on feared champs. Definitely increase the healing from passive on feared champs. Either give Noc's ult vision of champs below 20% health, or increase ult range and decrease cooldown.