A battle standard of infernal power was a large battle standard made from iron that was forged in the Nine Hells. At the top of the battle standard was a small cage that could not be opened. Within the cage was a quasit. If the quasit was killed, it vanished and a new one appeared within the cage.
The cage that held the quasit was invulnerable to nearly all damage. The bearer of this unique battle standard gained the ability to overpower other creatures' immunities or resistances, both innate and magical. The banner provided this ability to all creatures within 300 ft (91 m) who were allied with the bearer.