Ivar and Osmer were the strongest monsters at the Sacrificial Waterfalls, even though they were only Elders. It was a very high rank, they were comparable to Valdris at the Soaring Chain Islands, but it wasn't enough to own a large territory at the Dark Shore.
The reason was that the Sacrificial Waterfalls had a Lord like almost any region at the Dark Shore, but Ivar and Osmer's situation was unusual.
While they and their apprentices reported directly to the Befallen Crown, their Lord remained inactive most of the time and did not participate in their lives. The Lord of the Sacrificial Waterfalls was more like a landlord than a ruler.
Gladius killed all the monsters, but it didn't bother the Lord of the Sacrificial Waterfalls in any way.
But... What if Gladius wanted to take over the land?
It was rare, but as the Second Rank Phantom, especially of his level, he had that option.
Well, that could not be allowed to happen. There was an urgent need for intervention.