The Shroud

The Shroud has been the constant nightmare of Sarnil for millennia. Every great legendary monster, such asKithorun, The Tarrasque,The Elder Brain, and many more, were either born or created in The Shroud. All of these creatures are now thought to be gone, but other creatures still live there that scare any normal person (and most heroes) away. 
It is unclear how exactly The Shroud was cursed. The leading theory is that there may be some magical location, similar to the Dragon Tombs, that emits the poisonous energy across the landscape. Others think that an evil god may have cursed the location. Whatever the case, there appears to be a point somewhere in the center that has both the strongest effects on the creatures there. Monsters from The Shroud recently have been horribly mutated, and humanoids that travel there can become Shrouded. These people are driven to madness, sickness, violence, and a strange compulsion to travel back to The Shroud.
Anjeta is the only country that sends soldiers into The Shroud, and even then only on the outskirts to stop various monstrous threats. Recently, it was discovered that Warforged are immune to being Shrouded, leading many to believe that the condition is airborn. This has allowed for Anjeta, the leading technological nation, to send troops even further into The Shroud. Eventually, they want to cleanse The Shroud of its evil. There are many doubters as to their ability to succeed, but considering the lack of horrifying monsters that have gotten past their defenses recently, The Shroud seems contained, for now. But if history is any indication, it won't last long.