Step 1: Obtain 20 x Abyssal FragmentThis is the most time consuming part of getting the Nazjatar Blood Serpent. These fragments can drop from a lot of different sources, such as:
- Mobs in Mythic Shrine of the Storm.
- All Nagas in BfA zones (including Warfront zones).
- All human cultists in Kul Tiras.
- Void creatures in BfA zones.
- Battleground rewards chests.
The drop rate is extremely low, and people have reported farming these mobs for several hours before getting an Abyssal Fragment. The Abyssal Fragments used to drop from all level 120 mobs in the BfA beta, but this is no longer the case, so just focus on the mobs on the list above.
The Abyssal Fragments can also be bought and sold on the Auction House, so it might be worth picking up a few from the AH if you want to speed up the process of farming all 20 of them.
Step 2: Head to Altar of the Abyss in Stormsong ValleyOnce you have all 20 Abyssal Fragments, head to 73.50, 23.61 in Stormsong Valley and go behind the waterfall. There is a cave there which hosts an altar at the back of it.
Step 3: Offer your fragments and kill the Adherent of the Abyss bossRight click on the Abyssal Fragments close to the altar to summon the boss Adherent of the Abyss. Some users say that it's fine to fight it solo, while others say that you need at least 2-3 people for it. Anyway, kill this boss to loot your Nazjatar Blood Serpent!
Only the person who offered the 20 Abyssal Fragments can loot the mount, so unfortunately you cannot let your friends or guild mates have one of them as well.