Backstabbed in a Backwater Dungeon Vol. 9 (manga)

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!