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) They were capable of reconstructing themselves from any material, including the bodies of their victims, to repair battle damage. (AUDIO: Berserker)

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)

Berserker Daleks were part of the Daleks’ attack on Sunspire which wiped out most of the population. One became trapped in a bunker containing the natives’ gene bank and was left there for centuries, attacking the walls of the facility as it became increasingly insane. It was disturbed when a team of survivors along with the War Doctor and berserker-class cyborg Case entered the bunker, killing most of the survivors. Upon discovering Case it attempted to use her to reconstruct itself however she was too much for it, resulting in the two merging to become something new. (AUDIO: Berserker)

Berserker Daleks were used during the Daleks’ attack on Memnos, being ordered to break into a Dalek harvester which the Doctor and Case were hiding in. (AUDIO: Memnos)