Sesa 'Refumee

Sesa 'Refumee was the leader of the heretics, who have made camp on the Gas Mine of  Threshold and on Basis, the gas giant and its moon of which Installation 04 rests between.

The Heretic Leader commanded an Artifact Retrieval Group attached to the Covenant fleet at the first Halo ring. Busy investigating a Forerunner mining facility in the upper atmosphere of the gas-giant, Threshold, ‘Refumee was fortunate not to be on the ring when the Master Chief blew it up. The Heretic Leader first encountered Halo’s monitor, 343 Guilty Spark, a few days after Halo’s destruction. The Monitor “edified” him about the true nature of Halo, the fate of the Forerunners and the origins of the Flood. This knowledge inspired ‘Refumee and his Elites to rebel against the Prophets – a decision that led to outright civil war.

The Heretic Leader was branded as a traitor by the High Prophet of Truth, and for that reason, sent the Arbiter to deal with him. As he attempted to make his escape in a Seraph fighter ship, the Arbiter found him and fought him. Despite his clever use of Holo-Drones, the Arbiter sucessfully killed 'Refumee.

With the Heretic Leader’s death at the hands of the Arbiter, the specifics of the Monitor’s revelations may be lost forever.

Combat
For all intents and purposes, the Heretic Leader, on his own, is just a Ranger Elite with differently-coloured armour.

However, what makes the fight with him difficult is that he does not fight alone. As seen in the pre-battle cutscene, he creates two holographic doubles to fight alongside him. While these doubles are holographic images, their damage is, strangely enough, all too real.

On Easy and Normal difficulties it is enough just to ignore the drones on the floor and kill him when he takes off from the top of the fighter.

On Heroic difficulty, the easiest option is to just wipe out each Heretic Leader individually,using the Energy Sword and active camo to sneak up on them, taking cover when you need to. (Note:You can find an Energy Sword off to the right at the side of the hangar if you haven't got one already)

Quotes

 * "What did the Prophets promise you, Arbiter? A new command? A new fleet? Or was it the promise of their Great Journey?"
 * "The Elites are blind, Arbiter, but I will make them see."
 * "I'd rather die by your hand than let the Prophets lead me to slaughter."
 * "I see the Prophets have chosen poorly, Arbiter!" to the Arbiter if you fail to hit him on Heroic difficulty.
 * "Come Holy Oracle, we have much work to do." If he kills you on normal.
 * "And where are these "gods" the Prophets would have us worship? Transcended? Haha, hardly! Come Arbiter, let me show you where they went." (During a lull in combat on Legendary)

Production Notes
Sesa 'Refumee was voiced by Miguel Ferrer in Halo 2.

He appeared in the following Halo 2 levels:
 * Halo 2
 * The Arbiter
 * The Oracle

Joyride Studios released a Heretic Leader Action Figure in series 8 of their Halo 2 8 inch action figure collection.