The Hellborn Nightmare is another exclusive Vortex event made for the global version of Brave Frontier which was released during the Halloween season.
The Vortex dungeon is consisted four (4) levels, which the latter or the last stage requires a unit made and released specifically for the event.
Lv. 1 - The Path Less Travelled
Lv. 2 - Demented Trails
Lv. 3 - The Haunted Lands
Lv. 4 - Demonic Vindication, this stage requires the following units to enter;
The event will allow you to craft unique spheres made for the event.