Quote from: Cuer
My understanding of aggro is that it is not directly based on how much xp you get from the mob. I believe a standard aggressive mob will aggro anyone who is not 10+ levels higher than the mob's level. (Or maybe it's 11+ levels, I remember the "10 level difference" sticking in my head.) Since the exp you get (or whether you get xp at all) from a mob 10 or more levels below changes based on your level, that's not a good indicator. If you kill a mob 10 levels lower than you when you are level 15, you won't get any xp from it; you will get xp from a mob 10 levels lower than you at level 75. The corresponding way that most people explain it (If a mob /checks as Too Weak, it won't aggro you) is technically correct, but incomplete; high level characters can kill some Easy Prey mobs that they get experience from, who won't aggro them.

The extra factors that cause a mob to aggro are probably what kicked in here. The Aggressive to Low HP that all Undead have will activate regardless of level. The same is true for Aggressive to Resting mobs; they will aggro someone 50 levels higher, if the character rests near them. Oddly enough, this is not the case for the Aggressive to Casting Magic behavior: you can cast spells near an Elemental 20 levels lower than you, and they will never aggro from it.

I would guess that you were down some HP when you went by the Fallen mobs, and they aggroed from that. The Aggressive to Low HP behavior acts as a sliding scale: the lower percentage HP you have, the farther away the mob can be and still aggro you. I've never tested the reverse of this, to see if a lower level Undead mob will aggro you when you're missing just a sliver of HP, if you walk directly over them. But it may be the case that they can aggro even if you are very near full HP, if you get close enough to them.