Anti-S'kytri virus

The Anti-S'Kytri virus was a biological pathogen created by the Lycari several thousand years before the Battle of Yavin. It was only ever used once, during the S'Kytri-Lycari war and had devestating affect against its S'Kytri targets.

But the weapon also had adverse affects which allowed the S'Kytri to evolve into the much stronger Skrini.