Rogul is a character in Nexo Knights.
The Roguls were originally created by Merlok to store the forbidden powers within them. A combination of the Forbidden Powers and the Cloud of Monstrox' evil lightning caused the Roguls to become members of the Stone Monster Army.
The first Rogul was awaken by the Cloud of Monstrox where it was associated with the Forbidden Power of Relentless Rust in which anything that has metal on it gets rusted by it's touch.
The second Rogul was awaken by the Cloud of Monstrox in a swamp location where it was associated with the Forbidden Power of Ravaging Rot.