> > The spoiler I have read suggests that the Joker will have stolen the assorted Mob's money, so essentially he has their entire income as a hostage, and they HAVE to work for him.
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> Because they can't bop him over the head, tie him up, and torture him until he tells them where the money is? (I don't expect you to have the answer to that question.)

Or more simply he's contaminated the money with Joker venom, so they know where it is, they simply can't use any of it unless he gives them the counteragent.