I encountered one of the options. I defeated the improved druids; even the dog did well against them, along with the griffins. But how do you defeat many improved dragons, or hundreds of succubi, or viziers of genies? There's no meat, and there's barely enough magic. Moreover, the viziers were guarding an artifact from the set, which could be very useful.
Also, why can't you ban neutral creatures that are immune to the wave spell, in addition to those that are invulnerable to magic?
There are many questions.
Moreover, you move in a tight formation, and it still depends on the starting conditions.