Having stumbled upon the toxic, terra-charged territory of Arbourhome Blight, once home to the only Farslayer city of the Shattered Isles, you traveled across the series of islands, eventually reaching a giant tree.

When you arrived, there was an arena, and in it, a giant tree. When you approached, the tree began to move and shift, revealing it was a Behemoth, more specifically, the Keystone Behemoth, Agarus.