Does the Diabolous Wing's bonus damage effect the monsters for the whole quest line? Would be pleased to have bonus damage applied to Isle of Bios and Morse's Cave instances as well but as it's written it sounds like it would only effect the final instance. Also I don't have a character on Sakray that can test those areas if someone wouldn't mind taking a look.
Seems to only affect mobs that spawn in Temple of Demon God (魔神殿).