Champion monsters are often surrounded by minions. In some cases, I've seen these minions inherit the magical properties of their masters, but this is not always the case. For instance, sometimes minions of a nightmarish monster are also nightmarish.
What causes a minion to inherit the master's abilities? Does it always happen for certain abilities, but not for others? What about when multiple abilities are available on the unique monster? Are all inherited by the minions, or is there a cap?