Kav's force was dealt a humiliating defeat at the hands of the Chiss commander Thrawn and Kav himself was killed soon afterward by a blaster shot that ricocheted off of a reversed personal shield taken from a droideka when he tried to avenge his pride against Thrawn.
Siv Kav's first appearance was when he was found wedged hidden in the holo alcove off the cockpit's aft bulkhead of Kinman Doriana's ship. He had apparently boarded the ship while Doriana was meeting with Captain Pakmillu to receive the passenger list of Outbound Flight. Through further questioning, Kav admitted to hiding in Doriana's ship to find out Doriana's true name and position instead of waiting in the guest cabin as he had been instructed to. After he found this out, Doriana ordered Kav to forget that he had ever heard his true name and position and to refer to Doriana instead as "Commander Stratis", the name that Doriana had told Kav before.
The intention of this meeting was for Kav to give Doriana the coordinates to the separatist fleet that Kav had put together to destroy Outbound Flight. Kav gave Doriana the datacard containing the coordinates, and they left shortly after. They got to the fleet two days later.
While aboard the command ship, Darkvenge, of Special Task Force One, Commander Mitth'raw'nuruodo (Thrawn) made contact, stating his name, the name of his defense fleet, and asked to identify themselves and to state their intentions. Unsure of what he should do, Kav woke Doriana from his slumber. Doriana wasn't impressed. He asked Kav to open a hailing channel and explained to the Commander that they mean no harm to him or his people and that the details of their mission must remain confidential. In turn, Thrawn told Doriana that his reassurances were insufficient. Beside Doriana, Kav started complaining that this was a waste of his time. Doriana quickly hit the mute button and started arguing with Kav. Kav wanted to destroy Thrawn and his defense fleet while Doriana argued that he first wants to find out who they are and where they come from. Kav told Doriana that he was in charge of Special Task Force One, not Doriana. Kav decided to attack using the Vulture droids from Keeper, one of his battleships.
Thrawn first let the battle wage a while, then jammed the signal going out to the Vultures. The Vultures shut down, continuing in the direction they were going when they were active. The alien fighters started easily picking off all the inactive ships one by one. The Trade Federation fleet struggled to regain control of them using laser communications. Kav tried launching missiles from his Hardcell-class interstellar transports. The missiles locked on to the alien fighters, but the fighters deployed Conner nets. The missiles intercepted with them and detonated. Thrawn sent missiles of his own at the Techno Union ships. To Kav's dismay, one of the missile clusters found a weak spot and destroyed one of the ships. Thrawn targeted the same spot on all of the other Techno Union ships, destroying them all. Kav decided to make a jump to lightspeed but the hyperdrive didn't respond. Siv Kav admitted defeat. Doriana ordered the Neimoidians running the ship to close down the midline quad laser batteries, seal the main hangar exits, shut down all the droid starfighters, and to prepare for company.
Doriana and Kav met Thrawn and Jorj Car'das on the bridge of the Darkvenge with dozens of battle droids. Thrawn did not hesitate to introduce himself to "Commander Stratis". Kav was furious. He told Thrawn that he was the commander of the fleet, not Stratis. He also went on to say that he had the power to destroy Thrawn where he now stands, as two Droidekas rolled up and unfolded behind him. Stratis became angry and started to get in another argument with Kav, but Thrawn told him to remain calm and assured the commander that he was in no danger. Stratis was stunned. Thrawn went on to say that the Droidekas had interesting designs and commented on their shields. Then told Kav to order them away. At first it seemed like Kav was going to protest, but then he reluctantly did as Thrawn said. Thrawn, once again, asked them to state the intentions of their task force. Stratis invited them into Kav's office to explain everything there.
In Kav's office, Stratis seated himself in Kav's chair. He explained what Outbound Flight was to Thrawn and Car'das but then went on to say that while in the system of the Chiss (the name of Thrawn's people), the Jedi aboard Outbound Flight would attempt to impose their will against the Chiss. Before he left, Thrawn ordered Stratis and Kav to remain aboard the bridge of the Darkvenge and told them that he would send for them when he wished to see them. He also said that he would send a team to examine the vessel and it's equipment. Kav started to protest, but Stratis cut him off. Thrawn left and Kav started protesting in anger, asking if Doriana had any idea what he was doing. Doriana explained to him that there's no way their one remaining ship could destroy Outbound Flight by itself. The support of Thrawn and his fleet was their only hope of succeeding with their mission.
Thrawn took control of Darkvenge's complement of battle droids and droid starfighters and made Doriana and Kav effectively prisoners. However, he agreed to take whatever action was necessary to prevent Outbound Flight's mission. Thrawn made his own alterations to the programming of the droid starfighters to make them attack enemy ships at close range. Kav believed that this was an absurd idea, and implemented his own program following traditional battle logic. Soon, Thrawn intercepted Outbound Flight using a gravity well projector. When Kav attempted to activate his program, Thrawn revealed that he had already detected and deleted his additional programming. Thrawn opted to first try negotiation with Outbound Flight, to Kav's dismay. Negotiations ultimately broke down, and Thrawn disabled Outbound Flight's weapons systems. Kav again urged Thrawn to destroy Outbound Flight, but Thrawn decided to give them another chance to turn back. Kav witnessed as the leader of Outbound Flight, the fallen Jedi Master Jorus C'baoth, Force choked Thrawn. Thrawn was saved when Doriana sent the droid starfighters to finally destroy Outbound Flight, as Kav did nothing.
After the battle, Kav gave Doriana a Hold-out blaster he had kept hidden and told him to kill Thrawn. Thrawn released the two prisoners and returned them to the Darkvenge. This gave Doriana the chance to kill Thrawn, but he decided that killing such a brilliant military mind would be wrong. Kav disagreed, and took a hidden blaster from his desk chair. He shot at Thrawn, but the shot was deflected back at him by a polarity-reversed deflector shield Thrawn had placed on the chair, having anticipated Kav's betrayal. Kav died instantly.
Siv Kav was greedy and cowardly, similar to many other Neimoidians.