Looking at your screen, is that one of those weirdo levelup dungeons?
Yup, the latest challenge dungeon in JP is legend mode, aka weirdo levelup system.
Lv9 pits you against stuff like Dark Fagan, Drall from Diagoldos, and of course Nordis with his immense 8.5mil hp (17mil for green/light teams).
Lv10 have you face off Satan with your team at lv1 straight off wave 1. Then Straitos, Beelzebub, Athena, and Awoken Goemon. This lineup would've made it the easiest lv10 ever if not for legend mode :v
Basically, it's annoying and you have no idea how much your team will deal or how much you can heal because your stats are all over the place.
Part of the reason lv9 took me so many tries is I basically found out how many TPAs I need to kill this or kill that by trial and error.
Time for lv10! welp