If it wasn't already known, if you have more than 15 mobs and you perform an AOE action on it like Sleepga, Lullaby, AOE WS, etc., all of the above will take effect on everything there, however, the log will only show the 1st 15 taking damage, getting slept, etc. Same goes for Exp, if more than 15 died at the exact same time, only the 1st 15 show in the log (you still get all the exp/cp).

An empty enmity table is created for everything beyond the 1st 15 as evidenced by for example, if you Horde Lullaby the pack and a WHM heals you, any mob beyond the 15 after waking up will attack the WHM despite the 1st persons supposed enmity it'd have.

Since the enmity table is "zero" for the 'beyond 15 mobs,' would they all get TH applied if the AOE person was let's say a THF and using Aeolian Edge? This is quite the question!