Slugterra: Ghoul from Beyond

Slugterra Ghoul from Beyond is a 2014 Canadian animated film produced by Nerd Corps Entertainment and distributed by Disney XD Canada. It premiered on March 30, 2014 on Disney XD and is the first Slugterra movie.

Arriving there the group spots the Marauders rounding up every Fandango they can find, when they chase after them they appear to hit the edge of Slugterra. It is explained that the cavern is the Eastern most cavern in all of Slugterra, the only thing further east is a solid wall. The Marauders use the Fandagos to power a Terraportal to an Asian cavern system and brings through their leader the Dark Slinger, armed with a Ghoul Boon Doc, dubbed a Goon.During the fight Doc is sucked into the Slug ways and Burpy goes after him, which becomes highly problematic when the Goon is revealed to have the power to transform Slugs into ghouls, and is soon revealed to be the true leader of the Marauders. The Goon hits Eli and enters his mind it explains that the Dark Slinger was the protector of his cavern system, with the Ghouled Infernus he was wielding as proof, before he took him over. ........

Source: Wikipedia