Avitus

"Thrallslayer" was a Jiralhanae chieftain and a high-ranking commander within the Covenant's military. Possessing uncanny intelligence that complimented his violent nature, he is a dangerous foe despite his relatively small stature.

Biography
Thrallslayer was deployed with the Fleet of Glorious Interdiction by the Hierarchs to serve alongside Arbiter Ripa 'Moramee under the High Prophet of Regret during the Harvest campaign, despite his strong dislike of the Sangheili in general and 'Moramee in particular. During the campaign on Harvest, he grew to respect humans for their different nature and unfailing courage in the worst of situations. He enjoys eating thorn beast, which he prefers to be cooked rare, as well as hearing exaggerated tales of his adventures, told by an overweight Unggoy who serves as his official scribe. In 2528, Thrallslayer tore apart two Unggoy because his thorn beast was overcooked. The Unggoy were subsequently discovered as five organic chunks strewn about his quarters.

At some point according to Target_profile #43_867_37_, Thrallslayer was looking to regain some political clout within the Covenant.

In 2531, after the Fleet of Glorious Interdiction discovered the Etran Harborage, 'Moramee ordered Thrallslayer to accompany Regret when the Hierarch evacuated the shield world aboard the Proclamation's Tithe. 'Moramee's intent was to prevent Thrallslayer from earning any glory in the ensuing battle against the, but his actions would only ensure the chieftain's survival while the Arbiter himself perished at the hands of human forces.

In-game information
Thrallslayer will be automatically deployed as soon as the player finishes their first Temple. If that Chieftain is killed the player can purchase another for 400 resources, but can only have one Chieftain at a time. Thrallslayer uses a gravity hammer in combat and cannot hit aircraft unless using vortex. When activated, a spiraling vortex appears, tearing everything apart in range and explodes when canceled, causing additional damage.
 * Unique units
 * Type-25 Chopper: Available at the factory; replaces the Type-32 Ghost.
 * Jump Pack Jiralhanae: Armed with Type-25 Brute Shots.
 * Grunt squads are led by Brutes armed with Brute Shots, rather than by Elites armed with plasma rifles.
 * Upgrades
 * Tsunami: Increases Vortex damage and area of effect. Requires 400 resources and a tech level of 1.
 * Hurricane: Further increases Vortex damage and area of effect. Requires 600 resources and a tech level of 2.
 * Singularity: Further increases Vortex damage and area of effect. Requires 900 resources and a tech level of 3.
 * Leader ability - Vortex
 * Ability upgrades
 * Inheritance: Adds passive stun ability to normal attacks. Requires 300 resources and a tech level of 1.
 * Birthright: Can pull enemies to him during combat. Requires 500 resources and a tech level of 2.
 * Destiny: Adds an area of effect stun to the chieftain's gravity hammer. Requires 700 resources and a tech level of 3.

Trivia

 * Thrallslayer is voiced by Marc Worden.
 * He is the only playable hero unit in the game who does not appear in the game's campaign.
 * His Limited Edition leader card is the only leader card that has an image from any game besides Halo Wars: a picture of a Brute Chopper on the Halo 3 multiplayer map Sandtrap is used for illustration.
 * The armor worn by a Jiralhanae chieftain in the Halo Legends episode The Babysitter is almost identical to Thrallslayer's, though it is blue rather than red.
 * The twelfth terminal in Halo 2: Anniversary depicts a Jiralhanae wearing armor identical to Thrallslayer's killing Sangheili Councilors, though it is unclear whether the character is meant to be Thrallslayer.

List of appearances

 * Halo Wars
 * Halo: Fall of Reach
 * Invasion
 * Halo 2: Anniversary
 * Terminals