First I'd like to start by saying hello! I was skeptical of the community patch at first, but upon giving it a try fell in love. I really respect and admire what the community here has done with the game to carry on support for it. I've been a long time player myself, but very quiet in the past. I'm presently in college for programming: Javascript, Jquery, C#, and SQL. That's a bit about me. Now onto the topic.
I think the zealous doppelganger is an awesome skill. Summoning a shadow double of yourself with the same equipment and weapons is actually an extremely unique principle in RPG games, and helps set sacred 2 apart from (and above) the rest. However, the AI is still fairly buggy. While it was initially cool that he copied your skills and casts some of your combat arts, this seems to have reaped havok with his pathfinding and AI. I think he functions better in the community patch, but playing as much as I do, I still notice he misbehaves a lot more frequently than the shadow warrior's skeletons.
I propose a simplification of this skill and it's behavior. Instead of trying to cast spells (remove this from the AI completely), his focus would just be to run up and attack mobs like the shadow warrior's skeletons. I think many players would greatly appreciate the increased precision and combat effectiveness of their doppelganger. The aspect mods for the skill could also be changed (the second mod) so that the doppelganger spawns with a scaling permanent buff from the representative tree (would be cooler if the buff level was equal to the players). IE: the equal mod means he passively gains the effects of Purifying Chastisement. And the domination mod could give him reverse polarity. otherwise, he beats crap up like the shadow warrior's skeletons and we don't have to worry about his malfunctioning AI. Just a thought.
I'd also be willing to program this myself if you can point me to software that interfaces with the game, and submit my work to you guys for testing and possible implementation.
Thanks, ~From a grateful fan of the game.