The Great Forest Circle
In the center of the many Forests, there are these perfect circles, exactly 100 feet in diameter, where no plant life grows. When you walk into this ring, you get the sensation of your hair standing on end, and the temperature is substantially colder than it is outside the ring. The faint sound of cries for help can be heard, but they sound very far away and so faint that you cannot be sure it is real. It is whispered that there used to be a Wizard Tower in the areas, and due to a horrible magical mishap, they all popped out of existence. Casting Find Familiar here is rumored to provide a better chance of getting a rare creature.
Rumor is while in the circle it has this weakening effect, but for days after you leave you feel an amazing euphoria. rumor is that you are stronger and faster and smarter for days.