I May Be a Guild Receptionist, but I’ll Solo Any Boss to Clock Out on Time, Vol. 3 (manga)

The new dungeon, Chalk Tower, is riddled with unpredictable situations--first, boss-class foes wandering the halls, and then the annihilation of Rufus' party at the hands of an unknown enemy...! Silver Sword reluctantly opts for a temporary withdrawal. That means escape from adventuring duty for Alina, and a return at last to her beloved job as a receptionist! But for some reason, a sense of unease lingers... Meanwhile, Rufus joins Silver Sword as the vanguard and the party attempts to clear the Chalk Tower once more. But do they have any chance against a humanoid monster with Divine Relic!?