Always HB first after Pap dispels. I can't stress this enough Pap's boss chamber is by Spirit Vikings and Thanatos/Gatekeeper During the run if you have other experienced people, Pap might corner you against a wall. Switch to the other side of pap with the entire party. Don't stand on the platforms unless you want to get hit by boomers that deal 10k damage. When Pap temporarily shuts himself down, use Dragon Roar to destroy the blood booms.