There are numerous tales and stories about a great evil being sealed away only to awaken once more to bring war and destruction.
In most cases they are accompanied by prophecies about a hero or savoir who will slay the evil for good.
These evils can range from a powerful human to dragons or demons, even evil gods aren't uncommon.
In this case it is none of the above.
The greatest evil in the world of Terrastil is a being born from nature itself, but it started to defy its rules and order, causing great destruction and death to spread all over the world.
Its evil domain razed all life that didn't surrendered itself to it to the ground, be they tribes of lowly monsters, villages of peaceful farmers, cities full of people or powerful kingdoms, none were spared.
The apocalyptic rampage could only be stopped with the united power of all the gods and heroes, even then they lost an entire continent to the terrific monster and its domain.
With a great sacrifice they succeeded to imprison the evil in a separated dimension where it won't be able to cause any destruction.
To the horror of the world thought the foul domain of the beast didn't slow down in the slightest after its master was sealed away.
Only thanks to the assistance of multiple gods who gave up their freedom to power the complex and powerful seal which spans around the whole continent did the domain finally stop expanding.