Terror of the Night

Coming in Patch 11.2.

Don't be deceived by its bright colors, it is capable of sneaking up on anyone (or anything).

Riding Requirements:

Level 10
Apprentice Riding (ground)
Expert Riding (flying)

Source:

Achievement: Vigilante

Notes:

This green void swarmer is awarded by the achievement Vigilante which requires you to complete all six warrants in K'aresh. These warrants can be picked up as quests from a board located behind Constable Zo'ardaz in Tazavesh.

Travel Mode:

Ground (+60% or +100% speed)
Flying (+150%, +280% or +310% speed)

Speed depends on your riding skill.

Other Mounts Using the Same Model:

Terror of the Wastes

More info on Wowhead:

Terror of the Night taught by Terror of the Night