[This is all actually pretty informative, so Add is patiently listening and taking detailed mental notes. So the fog is what restrains the Creature, and the Creature controls the forest, and there's a separate barrier protecting the Grove... ugh, this is far too many moving parts. Why can't it even be something simple?]

But there are safe paths through the fog. Is that correct? [because Nene wouldn't have told him to get the glasses and visit if doing so would kill him, right? so the safe routes must be free of the fog's effects.] The pathways still show through the glasses, but the black fog acts differently. If whatever turned it black is a separate force, perhaps there's a way to resist it...

[or, if all else fails, maybe they can just acclimate to the horrible burning sensation? it doesn't seem like it left lasting damage, so hmm.]

If it was just the black fog, or just stray monsters, it wouldn't be a problem, but... [both of them at once, that's definitely a problem. trying to fight or avoid an enemy while under that much pain seems...]