The war had been going on for centuries, but while there were ideas of how to deal with the Daleks on a technological level, Weston believed that the only way for the Daleks to be defeated was to alter the mutants themselves. His ideas were controversial and some believed them to be the wrong way to deal with the Daleks.
It was so peaceful, that it could be touched by a human hand - usually a Kaled mutant would take the hand off. The Daleks were disgusted by this and organised a search for the mutant with the intention of destroying it, referring to it as the Abomination.
The Abomination was eventually found in a secret base of Weston's, but with the intervention of the Eleventh Doctor and the Space Security Service, the base was set to explode, destroying all the Daleks. When the Daleks halted the countdown, the Abomination became restless, broke free of its tank and pulled a lever which allowed the countdown to finish. All the Daleks died in the following eruption.
The Doctor did not believe the experiment would be successful but he did not witness the Abomination's actions. Unknown to everyone, the Abomination survived the eruption and waited on a ledge the magma had not reached. (COMIC: The Only Good Dalek)