[Help] Completing my sneak attack party

I've been wanting to make a party geared primarily (obviously not exclusively though) around sneak attack damage.  It started with wanting to make a Priest of Skaen as my Watcher, and then figured it could be fun to gear a party around sneak attack and disabling enemies. 

Just looking for general suggestions for class/role toround out the final 2 spots in the party for me.  It doesn't need complete overkill down to every talent/ability, just more of a sense of their role within the party.

My current thought for the roster is as follows:

1) (Watcher) Skaen Priest - Buffs, Interdiction, possibly Aggrandizing Radiance, melee (either 1h/shield or DW)

2) Rogue (melee) - Max sneak attack damage, sneak enabling effects, possibly 1h crit focused melee

3) Ranger (ranged) - animal with Merciless Companion, wounding shot + binding roots + stunning shots to keep sneaks up

4) Fighter - tank focused on engagement/knockdowns, helps with sneak to some degree and just need a solid tank

I don't feel like I have a good sense of what I'd like to feel the final 2 slots with.  One idea was a chanter with chants/invocations focused on lowering enemy defenses and also applying sneak-related debuffs.  Another was just a cc/de-buff wizard.

Any suggestions are appreciated.  (Note: this is likely for a hard/normal playthrough, not PotD)

Edited March 10, 20178 yr by HippoJ