In case anyone else gets it, I had the same error. Right-click jlauncher -> properties -> compatibility -> disable fullscreen optimization. Worked for me :/

Been a while since you've posted and im not sure you are still playing. But at least to answer the eye question, each stage is worth 15 dmg. Now when you use foe slayer, it should pop the eye buff thingy. If the eye is fully openned, it should d…

Would also like to know