I got some levels, quit game and restarted (so as to farm xp, due to monster respawn). Yet, i noticed hero monsters spawn in various locations, plus TWO TOGETHER AT A TIME! Also, i encountered something even more rare, not two, but THREE hero monsters that spawned together on the very same, small, spot of land... My shaman with that bramble... bristle... whatever his summon is called, owned them after a long, hard battle and the loot was fantastic (like 2 blues, some greens and many yellows); but i thought i read in the manual that two is the MAX number of hero monsters that can spawn together in the same area... Is that wrong?

Ah, that explains it, then! Thanks for the info! I have to be more careful in the future too, since i am hardcore and all (and have set the difficulty to veteran, as well)! But pays off, as far as i can see!

I've fought packs with 4+ heroes together. It's totally insane. Usually it's spiders or boars or something not so deadly like Harbingers or anything, but still a pretty heart-pumping experience.