Edit: So the class has changed and what a change the ambusher ability is now is a much more reasonable second attack while still rewarding clever play and no longer feels like it's broken, in addition, the bounty hunter's 7th level ability feels like a much better fit thematically and really plays to the strengths that the subclass seemed to be going for. So in light of both of these changes I'm revising my rating from a 3 to a solid 4.5 not perfect, I'm still unsure of seeing in magical darkness but probably the best attempt at a magicless Ranger I've ever seen.
So I meant to leave this at the same time I reviewed this on my channel but just got so busy I neglected to do so. However if you would like to see the full review head over to the link at the top.
In short the Slayer class (which was the Stalker Class) is a really good attempt at a Magicless Ranger however my concerns on balance and a few abilities make me hesitent to give it anything other than a 3 at this time. The abilities in question being the Ninja's Capstone, Ambusher and their ability to see in Magical Darkness.
I think this is still a great attempt and some fine tuning by the author perhaps changing the wording on Ambusher to only be triggerable once per combat, or something similar and maybe removing the ability to see in magical darkness would make me much happier to rate this far higher as there is a lot of good here.