Metebelis 3 was once known as the blue planet. Its moon was blue, its animals were blue, even the light was blue - and it was well-known for its large blue sapphires, found in the planet's mountains and apparently the cause of the all-pervading blue. But then things changed. A group of explorers crashed on Metebelis 3 after their starship came out of a time jump with no power left. While they began forming a colony, some of the spiders that had been residing in their starship were blown into the mountains. The mind-enlarging sapphires of Metebelis 3 began to affect them, and the spiders grew both larger and cleverer. In time, they began to rule over the humans. The word "spider" was forbidden - they now called themselves the Eight-Legs, and the humans became the stupid, lowly Two-Legs. The Eight-Legs twisted the minds of some Two-Legs and made them their slaves; the others, they ruled by fear and ruthlessness, even going so far as to kill a village of 269 people as punishment for hoarding food.
The blue crystals imbued the spiders with great powers. They have very strong mental powers - they maintain a constant mind-link with one another and can form links with Two-Legs. These mind-links enable them to either control the other mind or join with it, and either way they can inflict pain by twisting the other mind. This link works two ways, however, and a talented Two-Legs can just as easily twist the mind of the Eight-Legs. The Eight-Legs can also control people by jumping onto their back. Their powerful minds have also given them the ability to teleport objects, and if they have an anchor on another world - such as the ritual chanting in the monastery on Earth - they can use this to boost their teleportation range.
The spiders and those they possess can shoot electrical blue beams that stun or kill. Their personal guard are equipped with blue crystal weapons that have the same powers. These energy blasts can, however, be cancelled out through the use of a type of grey stone found on Metebelis 3. The spiders ordinarily feed on specially-bred sheep, but they prefer to eat humans. To this end, they may wrap their victims in silk and keep them in a kind of larder.
The spiders are organized in a council, all female, which is headed up by the Queen. The Queen spider is significantly larger than the others. These spiders all serve the Great One, an enormous spider who lives in a cave of blue crystals and has the ability to accurately mimic voices. By weaving a web of blue crystals that mimics her brain, she has been able to increase her mental power enormously - she is all-seeing, all-knowing and all-powerful, or so claim the other spiders. But her web is missing one crystal, the last perfect crystal of power - that taken by the Doctor during his previous visit to the planet. The Great One wants it back, badly, as the completion of the web will increase her mental power to infinity and put her in control of the entire universe. Unfortunately for her, she did not heed the Doctor's warnings that accomplishing this would create positive feedback and cause the energy to build up until it burnt out her brain, and the Great One and her followers were destroyed in her attempt.
