I Am the Legendary BOSS

What should I do if I travel through time and become an NPC? This idea took root deeply in William's mind! So, he decided. I want to become the strongest NPC in history. Build the thickest armor and get the hardest beating! Who said NPCs have to be killed by players? Who said NPCs have to upgrade slower than players? Who said NPCs must explode their equipment? I can explode even more... Bah bah bah. It's impossible to die anyway, you can only fool the players, fool the NPCs, and live a rough life. Hey, the chosen one in front, please stay. I see that you are not afraid of life and death. You are unparalleled in iron head. How about I sell you this legendary helmet for 100,000 gold coins?