The Witcher 3: 10 Hardest Boss Battles You MUST Find
3. Ignis Fatuus
Despite the absolutely ridiculous name, Mr. Fatuus is no joke.
He's easy to underestimate, considering he's just a slightly larger than average Foglet, yet Ignis is one of the hardest boss battles out there in the wilds of Crookback bog.
As part of the "Swamp Thing" quest, in which Geralt is charged with deducing why people seem to be disappearing in a supernatural mist, you'll quickly discover that the mist is actually the ancient Foglet hiding behind a small army of weaker Foglets.
What makes this fight especially tough is the Foglets' ability to turn invisible at will, meaning you'll seemingly be struck from all sides and nowhere at all. Ignis is also quick, so he's bloody hard enough to hit in the first place. His attacks also stagger Geralt, which means blocking's out of the question unless you want to be on the bottom of a swarming Foglet pile on.
It's even worse that most signs are useless here. Aard and Igni don't have a high enough chance to hit, as Ignis can simply dematerialise into fog before damage, and he's also immune to Yrden, the one spell that might have slowed him down.
Best to just cast Quen. And pray.