""Drat, out of healing potions."

The Eye Of Cthulhu was a chunk of eye that came off Cthulhu in the Great War. The power of Cthulhu still resonates within it, along with what brought the chunk back to life, demonite(or crimtane). This eye is hollowed out and replaced with power from Cthulhu, and corruption/crimson. This hollowing out is what makes it so weak."