Berserker Dalek

Berserker Daleks were a new breed of Dalek fielded in the Last Great Time War. They were deployed on simpler tasks, which required nothing more than extermination of a population, as they were incapable of strategy due to their lower intelligence. (AUDIO: Rewind)

History
Berserker Daleks raided the planet Lacuna, which the War Doctor attempted to defend only to arrive too late to stop the invasion. In a desperate gambit, he created a time loop of the last day before the planet was devastated using the TARDIS and spent hundreds of repeats trying to identify a timeline to save Lacuna, whilst the people of the planet endured remembering each cycle and their deaths repeating in them. He was finally convinced to break the loop and leave by Ignis Abel, though he promised to try to think of a way to return and save them in the 20 seconds left before the Daleks devastated Lacuna. (AUDIO: Rewind)