Tyr's Hand was now a wasteland, despite being quite a busy town before. Even so, the old knights of the town had managed to suppress the Undead to an extent.
Now, there was a war about to begin. Kel'Thuzad had deployed Heigan Lavender to Tyr's Hand to clean out the area.
The cleaning, in this context, naturally meant to completely turn Tyr's Hand into a fruit of the plague.
Heigan Lavender was once a Mage in the Dalaran. His interests were unusual, compared to the other Mages. While the other Mages would usually be obsessed with their Arcane Power and Elemental Summoning, he was instead interested in poison, micro-organisms and genetic modifications.
Dalaran was frustrated at his unethical practices. If it wasn't for his immense talent in Dark Magic, he would have been expelled from the organisation much earlier.
Of course, Heigan knew that the organisation wasn't happy with him. However, Arcane Power was worthless in his eyes.