The battle of the Oceans could not have been heard in the depths of the sea. Even when the Eye of the Ocean had opened fully and had revealed its ruinous stare, only half-eaten carcasses and debris reached the Nethergulf, the deepest part of the Ocean. Yet the sounds echoed through the abyssal wasteland nevertheless, as tectonic plates of the planet shook due to a meteor impact. They split and cracked and finally were torn apart, revealing chasms of nightmares and void. And from it something horrible and evil slipped into the world.
Denizens of Nethergulf were always known for their immense proportions. In the sunless wastes where distances are great and predators few, the creatures of deep sea outgrow their relatives of the shallows. Here the energy is conserved and rarely wasted, kept safely in the colossal bodies. Be it a cloud of singular jellyfish the length of the river or horrid angler fish with a haunting bioluminescence, here the time moves differently. And so, in Nethergulf the leviathans ruled their stagnant domain with slow and measured gait. Until Those Of The Below sniffed the life out of them and converted their flesh into Undead.
It was Nethergulf where the Undead Walkers originated. In husks of numerous sailors, mercenaries and merchants, they wandered aimlessly the depths of the Ocean. These Walkers primarily acted as one of the main food sources for those who inhabited Nethergulf for they knew not who they were or what has been done to them. Those who did have some of the life essence left in them had moved to the Reefs or Land and established their own communities. Yet now the countless lights blink in the seafloor, as the Undead Walkers are being woken.
None has seen or know what truly are Those Of The Below. Only the Tree of Life itself understands their purpose in the world. It is widely agreed by the tribes that in nature everything is in an eternal equilibrium. As there is a predator, there is a prey. As there is Light, there is Shadow. As there is living, there is unliving. These are not poles between good and evil but rather a symmetry of energy distributing itself. And if the living came from the Tree of Life, there has to be its opposite. A nemesis of life, which created the Undead. If one of the sides wins, the balance will be broken. If Those Of The Below, together with their vile magic, were released from their prison, the world will have to turn to chaos until the equilibrium resets.