I personally didn't like fan of knives, as an aoe ability, the cd is pretty high and not worth it. You also don't have any slow, except the 60% from the 10 sec cd FoK, and it def wont be enough. If you really want Impale, i'd suggest the Impact rune, mainly for bosses. Shadow power is fine, yet id rather pick the caltrops over it. You'd also lack a spammable AoE ability, like either multishot, cluster arrow, chakram or elemental arrow. Out of them, my 2 favs are def multishot and chakram. Also, brooding is pretty damn bad, id suggest archery over it.
Yet, this is just my opinion and im just level 37 as of now, and you'll have plenty of time to test it out yourself.
Yet, this is just my opinion and im just level 37 as of now, and you'll have plenty of time to test it out yourself.