Ah yes, I believe you are referring to the Occulent, looking at it in the eye can damage you, I know it's range is pretty far. Now this is a bug, and it seems you unfortunately had an encounter with it before it was properly documented on the wiki. If you log out while in a dimension, and you log back in, upon returning to the overworld, you may fall through the world into the void. It's still in the game, but it's easy to avoid if you just log out in the overworld. I'd recommend just playing the mod itself + a few small mods that improve the overall experience. I'll be honest, the addition of Tinkers in FTB Departed made it very meh for me, literally everyone and their mother love using Tinkers, and would rather use that than the many many weapons from AoA. Again, the OP has some info concerning some bugs and whatnot, and the Wiki has all the info you need about the content this mod offers. I know this because I've contributed it to it.