The boss has Demon Slayer, so don't bring Demon-type units. Also, all enemies in the dungeon are Light, so try to avoid bringing too many Dark units or else you'll take a lot of damage. The Specters will apply Bump Combo Locks to your entire team. Prioritize killing them, or else your run will take much longer. There are blocks in the dungeon, but they're not a big deal. Null Block isn't critical.