Chronoforges were devices created by the Time Lords of Gallifrey which were capable of creating weapons of temporal destruction. As a byproduct, they produced light (which was actually the bleeding off of photonic waste from fracturing chronons).
The Eighth Gallifrey of the Nine Gallifreys had Chronoforges and Loomstacks on its surface which were creating soldiers and weapons for use againts The Enemy in the Second War in Heaven. (EDA: The Taking of Planet 5)