Barbarous Dragon

Breeding
The can be bred by using a Oni Dragon and a Ragnarok Dragon, in either order, at the Breeding Cave/Epic Breeding Island.

Obtaining
The can be obtained by collecting a total of  12,032 during Whitbee's Candy Bash VI: The Haunted Hunt, but you must have all six of the  shroud pieces to unlock this dragon.

Earning Rates
Boost Calculation Guide to use with the page linked above.