The Friendship Arena is located in the far East corner of Dragon's Roost. It costs 34,800 gold and level 19 for the land.
At the Friendship Arena you can explore with 4 heroes at once! Friendship Arena takes 10 hours to explore. You will need a lot of wool for this because the items you need for exploration are a camping tent, 2 plain gloves, and 2 plain bandages. The camping tent takes 9 wool and 5 logs to make, the plain gloves take 4 wool each to make, and the plain bandages take 3 wool each to make.
You get 2125xp for each hero you send in. You also have a chance of getting a silver vault hinge, golden vault padlock, forest charm, emerald, and an iridescent scale. Good Luck!