An eternally thick, unnatural fog blankets the islands from the view of outsiders. It is thought that the islands are home to countless forms of undead, though no one seems eager to perform the exploration necessary to find out the truth.
Elise lures people here to feed Vilemaw in exchange for eternal youth.
"The Shadow Isles. . . They say they don't exist. Mythical islands haunted by ghosts and specters. Tales to frighten children. But I know better. I have been there. When I first set foot there I immediately knew something was wrong with that place. My skin crawled and in the pit of my stomach, I felt a terrible revulsion. Life didn't belong there. But I also knew... somehow, deep inside I knew that the islands welcomed me. They wanted me.
As I wandered deeper I saw death all around me. Ghostly trees, grass, and flowers engulfed me in their horrifying radiance. It was so quiet and so beautiful. I passed my hand through a spectral leaf fluttering in the wind, but there was no wind. That was when I understood that death was another world and I was at its door.
Then I heard the song; the spider's song. My companion cried out in terror and fell to his knees. I embraced him. I told him he had nothing to fear. He was going to a better place. I will take them all to a better place."
Treants are a fusion of nature spirits (or any sapient species) and plant life. One such species was the Omikayalan God-Willow, which essence was later transferred to the Freljordian warrior Ivern. Other example is Maokai, a nature spirit fused with the plant life and natural magicks of the Blessed Isles. Besides treants that share humanoid physical and sapient characteristics, there are those that take animalistic forms and behaviors such as those that take form of felines, lizards, or toads. A vast majority of these treants are corrupted by the undead magics of the Shadow Isles and have lost most of their sapience due to the Ruination. Maokai is among the being the very few Blessed Isles treants that survived such a fate.
Resembling that of an arachnid spider whose grotesque mass is furred and scabbed with wet, mutant growths. Adorned with venomous fangs and colossal legs used to heave its corrupt body. This unearthly horror is a monstrous creature that looms in the darkest pits beneath the Shadow Isles. The true origin of Vilemaw is completely unknown, save for the assumption that the voracious spider god is an otherworldly life-form not originally from Runeterra.
It has great physical strength as well as magical, being able to transfigure willing humans into its servants. It uses its servants to gather fresh food.