The Night Terror is a Stoker Class dragon released on December 26th, 2015. They can be purchased for 750 gems (600 for members) from the store.
From the How to Train Your Dragon Wiki:
- "Night Terrors are small dragons that are slightly larger than the Smothering Smokebreaths and the Terrible Terrors. Each individual Night Terror is black in color, except for the alpha. When they group together, especially at night, they appear to be all black in color and they form the shape of a larger dragon. They have small teeth and rounded tongue. They also have two small horn-like ledges on top of their nose. They also appear to have a short tail with four, short, thin spikes on the tail.
- The alpha is white and slightly larger than the others. It appears as an eye of the large dragon shape in the swarm. It leads the night terrors to form a giant form of them selves or other dragon.
- For more information on the Night Terror, visit here.