The Sky Burners are the "celestial demolitions" fleet of the Cabal. They are mainly based around Phobos, seeing limited deployment on Mars, as their full strength has not yet arrived into the system. In the base game, they are only encountered during the final phase of the Cerberus Vae III and Dust Palace strikes. It is likely that these are an advance force under the command of Valus Ta'aurc as when Ta'aurc dispatched the elite Ice Reapers to hunt down Rasputin the Sky Burners accompanied them as well. The Valus himself even used Sky Burner soldiers as his personal guard until his assassination. In both cases however the Sky Burners suffer total casualties.
The Sky Burners play a larger role in The Taken King as they are found on Phobos and the Dreadnaught.The Sky Burners are one of the first Cabal units to encounter the Taken and are routed utterly within hours, being forced to evacuate Fleetbase Korus.
They were originally led by Primus Ta'aun before he was taken. The Sky Burners were ordered by the Emperor himself to board the Dreadnaught and kill Oryx, the Taken King, by any means necessary. They crashed their warship into the Dreadnaught's hull, and are fighting a protracted war of attrition deep behind enemy lines. They can be identified by their light red/blue armor and brush on their helmets.