Backstabbed in a Backwater Dungeon: My Party... (Manga) Vol. 09

Light and his mighty Level 9,999 party members chase Sionne down into her dungeon laboratory! Before they go, though, Light swings by his Card Repository to stock up...and prepare a special surprise for the diabolical dark elf. An ambush by the sinister Blade of the Isles turns out to be a mere speed bump along Light's path into the depths of Sionne's dungeon—and the next step in his revenge plot!

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)