From the looks of things, the perimeter had 3 layers of protection. Two layers of undead guards holding the perimeter line, and a bunch of creatures hidden somewhere within the decayed forest watching over. If not for his earth sense, perhaps he would've fallen for the trap.
~Are they... building?~ Lucius thought to himself as he noticed an odd-looking structure just out in the distance. Pushing himself to the limit, he quickly dashed from tree to tree, going higher up with each leap.
~Oh lord,~ he thought to himself as he watched a group of undead shrooms using the Elmando skill to build what looked like the foundation for a massive structure.
~So they retain their skills even after they're dead?~ he thought to himself. He was unsure what skills the other sentients had, but this was bound to spell trouble if the necromancer somehow managed to kill a creature on the level of a furry-folk.