At his cavern , Finn defeats a group of fairies and then discovers a bucket list penned by Billy .
She delivers Billy 's loincloth to Finn , and Finn and she venture back to Billy 's lair to pay their respects and move on .
At Finn 's cavern Finn Finn defeats a group of fairies and then discovers a bucket list penned by Billy .
She delivers Billy 's loincloth to Finn , and Finn and she venture back to Billy 's lair to pay their respects and move on .