I hadn't tried it in 2 different playthroughs because it's rated really low online. But since I've used the other builds already, I figured I'd give it a go for Astarion in this new playthrough. He has an item that makes him invisible for two turns whenever he kills someone, which basically makes him a one man killing machine. For 3 different battles now I've split him off from the group and sent him out ahead to sneak attack the enemy group. Welp, reinforcements were never needed. He sneak attacks from range, turns invisible, moves away so he can't be detected, and attacks again. Each attack one-shots his victim, and he can make quick work of entire groups of enemies.

I can see that this build wouldn't be great for unexpected battles, or outright confrontation, but when you know that you want to fight, dang man! It's amazing.

If you happen to find that item that gives invisibility on kill, then I highly suggest getting a good bow, and giving assassin a try. It seems like it would be a good option for a playthrough without companions, as long as you are able to get back into stealth after attacking.