I've always pretty much ignored backstabbing through all my of my runthroughs, so I wanted to make a character built mostly around backstabbing. The optimal choices seem to be Elf or Shorties, and either Assassin, F/T, M/T, or F/M/T
I'm gonna talk a little about what I think of each combo, but I've only really tried out Assassin fully for backstabbing purposes, then I'd like anyone to share your thoughts on each Class/Kit for backstabbing purposes.
Assassin - Up to 4x Backstab multiplier by the end of BG 1 EE, Plus the poison weapons. However, I found the backstab successful hit rate to be very low, especially for Plate and Above enemies. Constantly had to abuse Invisibility since Hide in Shadows doesn't seem to work that well even with > 100 Skill. Enemies with high AC are pretty much 90% immune to backstab since you rarely hit them.
F/T - This one has a lower Backstab multiplier, but I would think the improved weapon proficiencies, fighter thac0, and fighter attacks per round would make this better at backstabbing than Assassin, but I haven't tried yet.
Any M/T or F/M/T combo: You get the added bonus of casting spells to make backstabbing easier, but I prefer to just have another separate Mage to do this for me.
C/T - There are a select few Cleric spells that can make backstabbing more reliable/better, but I'd still rather have a separate Cleric/Fighter or something to boost me up. The only exception to this C/T and M/T rule is that some spells only apply to yourself
Also, include any tips and tricks you use for backstabbing- I know there's a lot of spells like Invisibility and Mislead that can make backstabbing a lot more reliable, but I'm sure there's a few I haven't thought of before.
I just realized it was possible to backstab while wearing a shield, I figured it would disable all thieving skills, this makes it a little less risky to go in for backstabs near groups of enemies. As long as you don't need the melee damage aside from backstabbing it can be useful