The Absolution was a Covenant Destroyer attatched to the Combined Fleet of Righteous Purpose.
It was part of the Incorruptible's task force to Onyx. After the Sentinels of Onyx destroyed the Far Sight Lost, Fleet Master Voro 'Mantakree ordered the Absolution to make a pinpoint slipspace jump to the northern pole of the planet and scout for any targets of value. Somehow, the Sentinels were able to harness the slipspace drive of the ship, as they engaged in slipspace jumps themselves, and were lined up perfectly to destroy the Absolution as soon as it emerged from slipspace, which they did.