WUCHANG: Fallen Feathers

In the Shu temple on the very top floor there is a boss, and you can summon an NPC to it. You meet this NPC after you have defeated the first boss (the ogre) and received the key and opened the gate, there is also a shrine next to this boss and a merchant sits (at that moment we are just chatting with him, he does not sell anything yet), so after opening the gate, go forward, cross the river on a log and meet this NPC, he is standing by a tree in a hat, when we talk to him, he will blow a whistle and in the arena with the boss in the Shu temple you can use it.