Are there any sites with good boss AI and ability descriptions?

[Treesh]

Yeah, i'm honestly not sure. Many people have been trying to figure that one out, and yet so far that i've seen, people have only discovered how to force him to use it. For what it's worth, I don't think keeping him slightly offscreen stops him from teleporting judging from that video. The way they anticipate his teleport is because he stops moving on the minimap...which is just off screen.

I can say definitively that keeping him slightly off screen does not work. That's what I was trying to do in the first place -- use a combination of Hydra and Magic Missle-Seeker while keeping him just off screen so I could avoid some of his other attacks. And, of course, he was teleporting onto me frequently.

I'll try the tactic of moving in closer to see if that prevents him from teleporting onto me when I get to him in normal. I've also found it helpful before taking on a boss in a new difficulty to go back and fight the boss on an old difficulty with a low dps weapon just to get the feel for a fight in a safe manner.

Keep in mind that "off screen" range changes depending on your resolution. I know when playing with other people they're able to see stuff that isn't even on my screen yet and they're standing right by me.