Having done a number of runs through OC (kudos to the design team for this sadistic little beast btw) I noticed something in the run last night. The mob pack just before the 3rd mini-boss portal was different.
The reason it caught my eye, is because on my first run through I nearly pulled what I thought was a single mob but noticed the foot of the witch VH boss thingy (as the rest of her was obscured by the environment) just in time.
Yet in last night's OC she wasn't there and there was a Bloodknight I don't remember seeing before. Which leads me to ask: Have ZOS put in dynamic mob packs? i.e. mob packs that can change composition each new instance? Or ... dare I say it ... is this a bug?