While under the command of Admiral Harkov at the Battle for Honor during the Galactic Civil War, Vondruln worked as an adviser to the admiral during his defection to the Rebel Alliance.
Vondruln informed Harkov of the transfer of Maarek Stele to the Victory-class Star Destroyer Protector. Possessing this information, Vondruln made arrangements for "an accident" to eliminate Stele, which precipitated the "Battle for Honor". Stele was able to evade the conspiracy to destroy him, fleeing to the safety of the Nebulon-B2 frigate Osprey and the Secret Order, leading to the Galactic Empire's discovery of Harkov's plot.
Afterwards, Admiral Harkov executed Vondruln for his failure to kill Stele.