Skishtari

The Skishtari were known as one of the most fiendish race in the universe.

Biology
Skishtari resembled giant golden cobras with scarlet eyes. (AG: Survivors in Space) The Skishtari laid eggs in the populace of inhabited worlds. Skishtari eggs took thirteen years to hatch. (AG: Tsar Wars) A Skishtari egg had a psychic link with its host. (AG: Aladdin Time)

Technology
Travelling through wormholes was second nature to the Skishtari. (AG: Tsar Wars) They regarded themselves as masters of genetic and spatial-dimensional engineering. (AG: Survivors in Space)

History
In 2011 the Fourth Doctor said that the Skishtari had ransacked planets in the galaxy for many decades. (AG: Tsar Wars)