Short and sweet, the Flame Spirit summoned by the Hellhound doesn't take fat damage from Banish and instead gets timed out like a corporeal being would.
But wait, there's more! During the next fight deeper into the temple Flame Knight and Flame Dancer are also unharmed by Banish despite their incorporeal natures.
But wait, there's more! During the next fight deeper into the temple Flame Knight and Flame Dancer are also unharmed by Banish despite their incorporeal natures.