Backstabbed in a Backwater Dungeon: My Party... (Manga) Vol. 08

Light has at last dealt out to Sasha the fate she had coming! Now it's time to take a trip to the beautiful Dark Elf Islands for a little rest, relaxation, and revenge! Sionne, the Dark Elf scientist who betrayed Light, is holed up in her laboratory...which also happens to be a fiendishly difficult, dimension-spanning dungeon! Is it tough enough to deter Light and his party of Level 9,999 companions?!

Full Title: Backstabbed in a Backwater Dungeon: My Trusted Companions Tried to Kill Me, But Thanks to the Gift of an Unlimited Gacha I Got LVL 9999 Friends and Am Out For Revenge on my Former Party Members and the World (Manga)