A mysterious underground passage with hidden quest items
The Rusted Old Bell is a reference to Wirt's Bell used as part of Diablo 3's Staff of Herding, which opened the way to Whimsyshire.
"On the day of his Accession, Lord Uacax followed the morning birds and then honored him with their song. He adopted their image as his crest."
Jabbering Gemstone, a reference to the Gibbering Gemstone also used as part of the Staff of Herding in Diablo 3.
"Although Lord Uacax was an orphan, he held great respect for his ancestors. Before embarking on his quest, he honored them thrice. He returned with the riches of the earth."
"A cunning beast terrorized the plains. Though Lord Uacax was untrained in combat he hunted and defeated this foe. He claimed the beast's weapon as a trophy."
Head to the Field of Giants in Nahantu, just North of Ichor Falls. Find three Cordycepic Zombies and defeat them together.