Vampire planet

A planet with an unknown name was the chosen hiding place of the King Vampire.

Development
K9 reported it had high technological prowess but the peoples were primitive. This was due to the Three Who Rule's ban on advanced technology. The scans were lilkely registering the Hydrax as the high technology. The inhabitants did have some hidden technology such as Radio transmitters. (DW: State of Decay)

Landscape
The planet resembled a level 2 system. A village was the its most prominent feature which was surrounded by forests and furthur afield were caves used by the rebels. In the centre of the village was the Hydrax, it had the appearance of a castle, rock built up around it so it appeared to be on a hill. Underneath it were caves containing the burial chamber of the King Vampire. (DW: State of Decay)

Further afield still were several smaller settlements. One of these were the lands of Zarn, with his dwelling known as the House of Zarn. (EDA: The Eight Doctors)

History
Fleeing the Time Lord-Vampire War, the King Vampire took the Hydrax, a human ship, as a source of blood. He then traveled into E-Space through a Charged Vacuum Emboitment and took refuge on the planet.

The King Vampire went underground beneath the Hydrax which stood vertically. Over time the Hydrax was surrounded by earth and took on the appearance of a castle. A village built up around it where villagers served the Three Who Rule who were in turn subservient to the King. (DW: State of Decay)

Visitors came from other vilages. They became infected by the vampires and returned home where they in turn infected the other residents. This process meant that most, if not all, of these outlying villages had a vampire in control. (EDA: The Eight Doctors)

The Fourth Doctor, Romana and Adric came to the planet and were introduced to the Three Who Rule. Adric agreed to become one of them and Romana was taken as a sacrifice. However, Adric turned on the Three and rescued her.

The Doctor made contact with Kalmar's rebels and they attacked the castle. The Time of Arising came around and the King began to rise from his chamber. The Doctor used a scout ship to impale him, killing the King in the process. Without contact with their ruler, the Three also died. (DW: State of Decay)

Before he left, the Doctor, Romana and Adric attended a party with the rebels to celebrate their victory. Hurda convinced Romana that she was needed to aid an ill person in another settlement. Eager to help, Romana followed but found herself led into a trap with Zarn taking her prisoner. The Eighth Doctor and the Fourth joined together to rescue her and Ivo killed Zarn. (EDA: The Eight Doctors)