a being who is prone to unpredictable fits of rage, often with violent intent that comes to an end with catastrophic results.
The aftermath of such fits is often unviewable, the carnage and slaughter that befalls the viewer often damages the eyes and mind beyond repair.
Burning corpses can often be found preceding such events.
"Yeah, Don't mess with that guy. He's a rossy"
"A can't believe the damage, looks like a rossy was here"