Zhaitan

After the ancient dragon Primordus awoke, Zhaitan arose from the depths. As it awoke, it raised the sunken peninsula of Orr, triggering earthquakes and tidal waves that destroyed entire cities across the Sea of Sorrows, including the Battle Isles and Lion's Arch, and capsized many Corsair ships. Zhaitan used its ancient powers to create an undead army composed of dead Orrians and Corsairs. This army stretched from the newly risen Orr, across the Strait of Malchor, to the beaches of the Ring of Fire Island Chain, blocking off passage to Cantha.