Blue Infernal Hellhound w/ Blue Flames & Rippled Belly
There is one tameable creature with this look.
Forsaken hunters automatically know how to tame undead creatures. Hunters of other races must learn the skill from a Simple Tome of Bone-Binding. The source of this book is yet to be determined but will probably not become available until the full Shadowlands expansion.
The 'rippled' belly effect of this look seems to be due to an incorrect texture assignation. It may be fixed in the future.
*Level scaling: In Shadowlands most NPCs will scale with the Hunter's level, within the constraints of their level range. Hunters can tame regular NPCs up to 2 levels higher than them, but can only tame elite NPCs of the hunter's level or below.