There was shouting, the smell of blood, and Scourge everywhere.
A fierce battle was raging, Horde and Alliance alike fighting side by side against a common foe. Human and Orc watching each others backs, Kal'Dorei, Forsaken, and Trolls casting protective spells and healing anything even remotely friendly, Draenei, Sin'Dorei, Tauren, Dwarf and Gnomes sending their pets into the fray and calling upon the darkest of magics. When the fight seemed won, however, the gate opened and Arthas himself stepped out, and an unnatural chill seeped into the fighters, but a red hot rage drove them forward.
There had been very few Forsaken fighting, only the ones who were friendly to the other races, and friendly to the Alliance, even through the Argent Dawn and the Circle. Most of the race was absent, and most figured it was their dislike of the living that kept them gone, but paid it little mind since Arthas was right there, within reach of all the blades and spells of the masses gathered to finally defeat him. The Forsaken who were fighting wore mismatching armors, but fought with a fever that didn't seem to possess most of the other fighters. A few stood out, wearing the green and brown colors of the Circle, the few life-loving Forsaken existing. One in particular was fighting and slinging shadow magic so fiercely that no one questioned that green energies entwined with the shadow, the faintest trace of leaves in the magic..
That's when all hell broke loose, really.
Someone had noticed, and snarled in disgust. He swung his arm down, giving the signal to sling the new plague into the fighting masses, intent on killing them all. Many were killed, some survived, he noticed, and some, like the Lich King, were weakened, but strong enough to retreat. There was a cry of rage, cut off by choking, and he smiled, his master's plan working. His smile, however, was quickly reversed into a frown when the Red Dragonflight arrived and vaporized the Plague. He could only grimace and think a few choice words before the fire consumed him as well.
Once the cloud of remaining plague dissipated, Horde and Alliance moved in to reclaim their dead to ship home and give them a proper burial.