Confront the Source is the final mission of Gloomy Manor in the Dark Moon Quest in Luigi’s Mansion 2 HD on the Nintendo Switch. The whole mission takes place in the cellar and is a fight against Gloomy Manor’s final boss, a giant, possessed spider.
To defeat the spider boss, you have to use fire to burn its webs, but it’s not at all obvious how to actually do that. It also gets more difficult to burn the webs at each stage of the fight. I was left scratching my head a couple of times during this one, but eventually, I figured it out and defeated the spider boss. You can complete Confront the Source using this mini Luigi’s Mansion 2 HD walkthrough.