Riftshards? The fuck?
If you're gonna actually go for your Auto Attack doing decent damage, get a Harkons Blade, not fucking Riftshards.. lolwat.
I always go Pkey, Portal Key for the fucking win. Best 2150 you'll invest in on Witch Slayer. Just run up, tele in, Stun / Ult some Int trying to lane, bam they dead, you walk away. When you res, do it again, it's probably the easiest way to farm kills with Witch Slayer. Also helps for Initiation (in team fights) and obviously escaping. Other then Ghost Marchers / Pkey I'll go either Support, or just grab a staff to make my ulti lolwtf.
Always get the Courier / Wards (one of the two, not both) at the start, for christ sakes. I'm sick and tired of seeing idiots not spend the 200 starting gold when they play Witch Slayer. WS is probably the best hero in teh game in regards to being able to cripple almost any hero without the use of ANY items. You don't need that 200 starting gold like a Carry will, so fucking help your team out.