Loque'nahak is a beautiful unique-skinned level 76 non-hostile rare Spirit Leopard with approximately 16.5k hp. He can be found in Sholazar basin in seven different locations which are indicated in green on the map below. He is one of three rare spawns located in this zone, all of which are unique tamable hunter pets. The other two rares are King Krush (green Devilsaur) and Aotona (blue & purple parrot).
Unfortunately for all of the hunters out there looking to tame him, he is part of the Northern Exposure and Frostbitten achievements so people will be hunting him down intent on killing him. He drops Loque'Nahak's Severed Fang which is a level 74 bind on equip neck item with a random enchant. He can also drop Loque'Nahak's Pelt which is a level 74 bind on equip cloak. The cloak can also be skinned from his corpse, so it is possible to see two of these cloaks off of one kill. Like other Northrend rares, he also drops Abandoned Adventurer's Satchel, which generally contains about 20 gold, a full stack of frostweave cloth, and often times a few crystallized elements.
Loque'nahak is a tamable hunter pet. Please note that because he is a hunter pet that even though you may not have seen him before in Sholazar Basin it doesn't mean that he isn't already cached by NPCScan. If a hunter has this tamed pet out near you, your NPCScan will cache it. If it is cached in NPCScan and this rare is up your alert will not go off. Be sure to check and clear your cache often!
Loque'nahak is a spirit beast, he can only be tamed by hunters that have the top-tier talent from the Beast Mastery tree Beast Mastery which allows the taming of exotic pets.
Loque'nahak doesn't really have any special abilities to note when fighting or taming him. I do recommend leaving him alone so that hunters can tame him unless of course you need him for the achievement. When tamed his special ability is Roar of Courage, exotic ability is Spirit Mend and his bonus ability is Spirit Walk.
Generally once tamed or killed you can expect to not see Loque'nahak spawn again for at least 6 hours.