While Blizzard has never given us the details on loot drops (as far as I know), they did however tell us that the loot on the bosses in instances like Molten Core are determined at spawn of the instance.

I would make an educated guess and tell you the mob's loot is determined when it spawns. It wouldn't make much sence to put in a separate process for mobs outside an instance, then in.

Everytime anyone has tried to put "rules" to the random loot system, eventually a Dev would come out and say "sorry, when we say it's random, it's random".

They pointed out that with so many people running the same game, a true random system (as they claim this is) will eventually give seemingly crazy results. One guild on our server ran MC for over a year, and NEVER saw the Might Pants.... EVER. That's random.

So I'd guess the loot is determined when the mob spawns, as a "random" system would have no need to determine it later.

Interesting thought though... Anyone have any information I don't?

Boom