A new island to colonize.
A commander and his small army arrives on a newly discovered continent. They also bring servants and slaves (adventurers). The map is invisible at the start, and only regions that have been taken over are visible. Since no humans have lived here before, the lands are inhabited by monsters (stationary groups).
Basically the Invasion, but the other way around
We don't need a new continent for that. Just a way to push back that blight and drive these abberations off of our lands!