Below is a walkthrough for A Realm in Peril side quest in Tiny Tina’s Wonderlands. To obtain this quest, speak with Paladin Mike in Izzy’s Frizzies in Brighthoof.
Clear 3 camps in Overworld
Follow the objectives to all 3 camps and complete the encounters.
Talk to Knight Intern
Head slightly south of the Queen’s Gate map transition to find Knight Intern and speak with him to complete the quest.
Head inside the newly opened gate behind him to retrieve the Shrine Piece!