Slave of the Hond
A being from outside time and space, to whom the Daleks referred as simply the Entity, was unleashed by the Archivians. It agreed to transport the people of Islos and the contents of the Archive to safety in return for the Daleks. The Chief Archivian let it through a portal as the Daleks were entering the Archive. (WC: The Archive of Islos)
It forced the Daleks to retreat from Islos and followed them back to Skaro. It began attacking the City, forcing the Daleks to evacuate the planet after finding their weapons were ineffective.
The Entity followed the Prime Strategist as he sought reinforcements from the Sentinel of the Fifth Galaxy and used its abilities from existing outside to time to take over the Sentinel prior to the Strategist’s arrival. The Strategist dismissed the Sentinel’s odd behaviour, such as referring to him as the Emperor, as defective programming and allowed it to awaken the dormant army and update the battle computer. The Entity took over the army, reprogramming the Daleks to recognise the Strategist as the Emperor. Through the Sentinel it revealed to the Strategist that, whilst it was seeking to eliminate the Daleks, it would settle for changing the leader. The Strategist refused and accelerated the self-destruct of the facility, destroying some of the army and a part of the Entity with them. Some of the Entity’s army escaped and purused the Strategist, engaging Dalek forces under the command of the Executioner. (WC: The Sentinel of the Fifth Galaxy)
The Entity devastated the Daleks’ forces. Knowing that it followed the Daleks, the Emperor of the Restoration deliberately led the Entity to Mechanus (WC: Planet of the Mechanoids) to force the Mechanoids to help the Daleks against it. When it arrived, a part of it took over a Mechanoid and issued an ultimatum, demanding the Emperor be surrendered. Mechanoid 2150 and the Strategist exploited this to identify energies unique to the Entity and managed to create a portal to send that part of the Entity back to its original dimension. The Entity attacked the City in full, breaking through the Mechanoids’ shield, and began striking the Emperor who the Mechanoid Queen had left in the open. The Strategist and Mechanoid 2150 used Mechanus’ orbital array to target the entire Entity with a portal, removing it from the universe. (WC: The Deadly Ally)