CASUAL OBSERVER
The forest air hung uneasily as living corpses ambled about aimlessly beneath the bare branches of Tirisfal Glade in the evenings growing gloom. Yet their unfocused behavior was noted by a concealed presence flying silent and low over the treetops. These undead were far more sluggish compared to the ones he had seen assaulting Undercity, a good sign. It meant there was no nearby Scourge lieutenant to control their attentions. Which also meant his temporary residence had little chance of being intruded upon any time soon.
Soaring steadily on over the mobs of stumbling cadavers and dead trees, he continued heading for a tall misty mountain in the distance. And in due course, a dark structure built against the side of the mountain loomed out of the mists. He smiled an invisible smile. For he had arrived.
The magically shrouded being noiselessly dropped to the ground a ways away to begin observing his immediate surroundings. Yet there was nothing but the eerie howls of the dark forest's feral occupants to detect. Eventually a steady gaze rose to the structure's tall battlements in a lengthy and intense perusal.
Finally satisfied at the lack of movement, large bat-like wings were stretched wide. And with a mighty leap and a downward thrust he launched into the air, becoming visible for the first time in days as his concealing spell was overstrained from his action. He quickly alighted upon an empty stretch of wall overlooking an inner courtyard of the infamous Shadowfang Keep.
He returned to the safety of invisibility to further scrutinize the fortifications inner workings. But he soon determined the place to still be abandoned after multiple Alliance and Horde forces had scoured the keep of its former ruler.
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He then flew up to the highest tower to perform one last check, before dropping into the tower through the hole provided by a partially caved in roof. It was only after a series of arcane ritual gestures were completed that the demon shed its invisibility, as the anti-scrying barriers took hold.
And as he listened to the howls sounding in the distance, Mal'Ganis, once high agent of Archimonde and general of the enslaved Lich King, set about his new task with a shark-like smile.
To prevent the swelling Scourge from conquering Azeroth, while paving the way for the Burning Legion's invasion. The smile faded. And perhaps getting his own revenge upon the upstart Lich King in the process...
SHADOWFANG KEEP
Day after day, the relentless demon set about collecting new live worgen to experiment upon as their predecessors perished.
Days into weeks, while Mal'Ganis experimented... the worgen were howling.
The results revealing two different strains of the wolf-like beasts.
The first were outright demons, denizens of the twisting nether, with a nose and hunger for mana. These were the ones that had found their way to Azeroth drawn by the uncontrolled magics of the naïve mana users of Dalaran. The demonic worgen were few in number as they were no longer drawn to this planet with the city's erasure by Archimonde. And were therefore useless to his purpose. They would however, be naturally be incorporated into the Legion when encountered in the future.
Weeks into months, as Mal'Ganis meticulously documented the differences... the worgen were howling.
The second strain he knew something about beforehand. A curse originating from the bites of rebel Druids imprisoned by the Night Elves. What was new was how a summoning gone wrong had contaminated a whole region of Humans with the worgen curse before being safely quarantined. And being able to spread made these cursed worgen useful, as the cunning Mal'Ganis's thoughts converged on a dark plan to accomplish the Burning Legion's desire.
A working plan... IF he could just figure out how to control them?!