Do not venture into the forest blind; make yourself immune to it!
Gloomrot – How not to be BLIND for Act III | The Curse of the Forest
One of the coolest additions to the Gloomrot update comes in the form of a rework of the Cursed Forest. Now, if you venture into the forest, you will receive a stacking debuff called Curse of the Forest.
What this debuff does is basically make your immediate surroundings shrouded in fog. Your minimap will also be covered. As such, it becomes much more difficult to explore the area.
This can be really annoying, especially if you visit there and try to farm some materials. Don't worry; you can easily remove it with a single item!