Two of the warriors managed to survive the onslaught of the Demons, while the rest are shredded by Scourge Casters and then cleaved into pieces by the Wrath Bringers.
Through sheet weight of numbers, the Necromancer appears to have the upper hand unless Cain calls the Seraphim or the Supporters back from their battles near the border, but none of his summons except the Bone Dragons were high quality.
He hasn't called them today, so either they're on the ability to cool down or require a reagent that the Necromancer doesn't have with him.
The combination of Dragon Breath and area damage is taking a lot out of the Undead, but the combination is even harder on the Necromancer. They can absorb a Summon every so often to heal, but the actual healers working with the group are dead. Cain watches as the Oath Breakers time their strikes to hit their larger undead targets all at once, killing the black-cloaked Necromancer in a single shot with the area damage.