The Iron Gronckle Dragons: Riders of Berk : Season 4 Episode 2
TV-Y7 (Universal Kids) Cartoon Network 22m
Aired: September 26th, 2013 @ 2:00 AM EST on Cartoon Network
When Meatlug accidentally ingests magnetic rocks, she becomes magnetic herself - causing destruction through the town, but ultimately helping the kids win a battle against the Outcasts.
