After Sora, The Beast and their friends dealt enough damage to the Shadow Stalker, the chains on it's body began to fall off. As a result, the Shadow Stalker's body began to mutate and transform into it's true form; the Dark Thorn. In this form, Dark Thorn loses it's ability to possess certain objects in the Beast's Castle, however it does gain a few other abilities, including becoming invisible. However, Sora was able to use the very elements that the Heartless had recently acquired to beat the Dark Thorn into submission. The mutated Heartless then faded back into darkness, forcing Xaldin to retreat and reform his plan.