What brings out Baal's minions?

[MongoJerry]

I have what may be a strange question, but it will be important for a new build I'm thinking of making. The question is besides actually killing the monster packs that appear, what triggers Baal to bring out the next set of minions in the Throne of Destruction? Let's say hypothetically that I have a character that is only allowed to cause fire damage and is not allowed to use a mercenary. Colenzo and Lister are both fire immune, so it would be impossible for this character to kill them. What exactly are the conditions necessary to cause Baal to go to the next minion pack (or in Lister's case, allow you to enter the Worldstone Chamber) without killing the prevous pack?

I think I remember something like if you wait a certain amount of time, the next pack will appear even if you don't kill the previous pack. What are the conditions that allow this? Do you have to get the previous pack and/or boss out of the main chamber or do you just have to wait? How long do you have to wait? 5 minutes? 10 minutes?

[adeyke]

It's enough to make sure there are no longer any monsters in his throne room. It's somewhat common practice to "park" minions outside if they're too tough to defeat and return to the room for the next wave. I'm not sure exactly what the boundaries are; it sometimes seemed like the side of the room opposite Baal counts as outside. I haven't heard anything about the next wave appearing if there are still monsters in the room.

[Assur]

Hi MJ

Just what new build are you going to create? Could we get a hint?

good hunting

P.S. Parking usually solves the problem of immunes.

[MongoJerry]

I'm keeping it a secret until the character's ready to enter hell. It's going to be an insane build, but I'm sure people will love it.