I opened up the toolset just to fix some jumping points as a bug workaround so we could finish our White Plume Mountain campaign and I started to fiddle with a small area and some creature AI-scripts I've been pushing away to a remote corner of my brain. It's not anything fancy just some fake co-operative behavior from the enemies side.
When the amount of monsters are down to 4 two of them starts to circle (opposite directions) the strongest PC or companion while the other 2 attacks the weakest.
If theres 3 monsters one they pack together attacking the strongest PC. One doing the circling but tries to do nasty weakening stuff when he gets a chance (as when the PC targets another monster) the other two alternates between attacks and moving away.
When they are down to 2, one of them attacks while the other one heal and buff (trying to heal the partner in crime if possible) then they shift. Combing the behavior of circling, moving away and attacking, makes even a weak group of enemies a real challenge and makes the combat fun from a tactical perspective. I just played 40 minutes or so and I think a player might get the idea and see through it so it should probably be about 10 different and maybe random combat dances to chose and combine for it to feel really intelligent.
Then I came to my senses and shut the computer down, went washing my hands and face. Toolset-fever. That was a close one!
(sorry about the English, I'm to lazy to try to read through and correct)