The Harbingers

These four losers, led by the Daemon who wishes he were the aspect of War, attempted to kill us after being paid by Theron Styx with the captured soul of Heleyna Styx.
* Slaughter and his Nightmare mount
* Ruin and his Intensified Empowered Fiendish Enlarged Super Unfriendly Rust Beast
* Swarm and his Taliban
* The Ferry Man (Heleyna) and her old nag, who might have also been Heleyna.
The party was captured by High Priest Theron, and used as a tool to destroy his rival-slash-ex-wife. 
With the death of Heleyna Styx, Charon begun to pay something approximating personal attention to The Great Downward. She offered her favor to them, but GDEC (very reasonably) responded by accepting money rather than ambiguous gratitude from one of the most evil creatures in existence.
Helayna, not knowing of Theron's treachery, entreated him to raise her. Instead he captured Helayna's soul, and sold it to Charon. In return, Charon lent him the use of the Harbingers, a mercenary group of daemons led by the purradaemon Slaughter, a deacon of Szuriel, the horseman of War.
Slaughter lured all of his targets to Pride, a demiplane of Abaddon, and the Harbinger's home, which had the advantage of preventing the escape of his prey. Included were Mort, Kruin and Erika, who had been pulled into the plane as well. Slaughter taunted them; while they were trapped fighting him, his troops marched on Dejune and Greyton.
There he challnged The Great Downward, along with the meladaemon Ruin and his rust-monster mount, the leukodaemon Swarm and his exploding horse, and the thanadaemon Ferryman; Helayna Styx given a new form, and wielding her Dacris.
Combat on the lakebed was short but bloody. The daemons proved formidable opponents, but the Engineers were better. Arrogance is the primary daemonic trait, but the Engineers had luck, bravery and a few tiny gods on their side.
With the daemons dead (even if they were still moving), the aspect of Szuriel entered the fray, and destroyed the Harbingers. This was not Abaddon's battle, and Szuriel was furious at Slaughter for getting him involved, saying that the horsemen were to have no part in the upcoming conflict, and would not interfere.
Szuriel wondered if Mortimer was powerful enough to make a god bleed, and allowed Mort to take a swing at the him. Mort (in typical duel-mode) botched the attempt, succeeding in only slicing a scrap of leather from Szuriel's boot. He said that the scrap of leather was an (un)holy relic. Should it be damaged or destroyed, Szuriel would be forced to smite those who had perpetrated the slight.
Szuriel opened a path back to the bloodways, before quitting the plane himself. He did mention that Orcus's plan posed no threat to him, but that it would create the kind of destruction that the horsemen desired. He wished the Engineers to return to the fight against Orcus, saying the battle would be far bloodier if the forces of good were strong enough to lose to Orcus by only a small margin.