Grey planned with the Peak Sovereign about a potential sneak attack, the benefit of having the space element is that they could catch the opponent with the element of surprise and hopefully take out some of their strong experts. When the man thought about it, he felt this was a good option since it would minimize the risk for them. The more people they are able to take out at the start, the better it would be for them.
According to the Bunny Leader, there was no portal there which meant the Gnomes set up camp here in order to monitor their activities.
The place where the Gnomes were hiding was in a well-hidden cave, surrounded by mountains making it hard to spot. If not for Grey's ability to sense Gnomes and Necromancers, it would have been impossible for Humans to ever suspect the Gnomes would be bold enough to set up camp so close to their supposed safe region.
