They are the most terrifying enemy in Halo. They have been known to bend reality, and use both Star roads and other precursor technology. Their intelligence level can he as high as the most advanced AI the Forerunners had. One Keymind can lead billions if nit trillions of troops. Once they form they are nearly impossible to stop. They are similar to a Gravemind, but much more powerful. All Keyminds start off as Graveminds.