- You may be looking for the deity.
The Eight Legs obeyed the Queen Spider, who also obeyed the Great One. Being physically a giant, the Great One lived in a cavern made of blue Metebelis crystals. With her psychic power she could read the Doctor's mind and discovered how fearful she made him. Obtaining the Doctor's crystal, which was the last perfect crystal she needed, she completed a web of the crystals which lay above her head and she was able to unlock her mind. She ignored the Doctor's warnings about the consequences of what she was about to do.
Infinite power and knowledge were fed into her mind, but since there was no way to vent it, radiation from the crystals built up in the web and the crystals burned her mind, destroying her. (TV: Planet of the Spiders)