Koven

Some kind of Elder God or spirit that seems to embody (and lay claim to) Samhain and Halloween. Though not actively malicious, he loves playing pranks almost as much as he loves eating sweet treats. When he's around humans or weak-willed creatures, they can become more mischevious themselves, though how depends on their personality. He can hop between dimensions at will, as long as that world celebrates a Halloween-like celebration, and his powers grow stronger the closer it gets to that time. It appears that he can twist the very fabric and laws of reality itself if he so wishes, and the mouth in his tail can devour souls, though it rarely opens. He seems to have a fondness for demons and humans, and will protect them from dangerous creatures if he can, though if spited he will cause chaos.