Build: v. 1.05
If you take the waystalker and fire arrow of kurnous at a target out of range, he will walk/run up to the target and fire.
However what some may have noticed is that if "fire at will" is on, every arrow he fires while running up to the main target will also be an arrow of kurnous. Meaning you can fire arrow of kurnous in rapid succesion(at off-targets) as long as the main target is out of range. I've added some screenshot to demonstrate the issue.
As you can see the arrow is triggered without going on cooldown. I have targeted some marauders on the other side of the map.
Again firing with no cooldown.
Lastly I fire manually and the ability goes on cooldown.