Rebuff Madam Von Bartlesby
"Rebuff Madam Von Bartlesby" is an objective in the sidequest You Are Cordially Invited: Party Prep in Borderlands 2
Head on out of Tiny Tina's Workshop and go to the Southwestern corner of the Tundra Express. This will lead you to the Skittering Mound. Here you will find Madam Von Bartlesby guarding Sir Reginald.
The Madam will take to the skies and start launching small Varkids at the Vault Hunter. She will also launch ground attacks, such as lunges and acidic spit at the Vault Hunter. Keep moving to avoid the worst of what she can do. When she goes down, you will be able to proceed.
Emancipate Sir Reginald