WoW Achievements — Browse All Achievements
Track all 8,600+ World of Warcraft achievements. Browse by expansion or category — Dungeons & Raids, Quests, Exploration, PvP, Professions, Reputation, and more. Sync your character to see completion progress.
Browse achievements from all expansions including The War Within, Midnight, Dragonflight, Shadowlands, and Classic. Find guides for Glory of the Raider, meta-achievements, PvP achievements, exploration, and more. Track your achievement points and completion progress via Battle.net.
That's Just Cruel
Defeat Nefarian within Blackwing Lair while the Onyxia Scale Cloak is equipped. Do the same within Blackwing Descent, just to get the point across.
That's Just Cruel requires you to defeat Nefarian in both Blackwing Lair and Blackwing Descent while wearing the 
Onyxia Scale Cloak.
Obtain Onyxia Scale Cloak
The Onyxia Scale Cloak is BOE, so you can purchase it from the Auction House or have a leatherworker alt craft one — you do not need to be a leatherworker yourself.
Clear Blackwing Lair's Razorgore
When you enter Blackwing Lair, do not simply nuke Razorgore or you will wipe and be locked out of the instance for up to a day. Instead, right-click the green orb to take control of Razorgore, then use its second ability to destroy every egg in the room before killing the boss normally.
Defeat Nefarian in Blackwing Lair
With the Onyxia Scale Cloak equipped, fight through Blackwing Lair and defeat Nefarian to earn the first part of the achievement.
Defeat Nefarian in Blackwing Descent
With the Onyxia Scale Cloak still equipped, enter Blackwing Descent and defeat Nefarian — complete Onyxia before Nefarian if the kill does not register credit immediately, as this may help the game register the achievement.
Tips
After completing both kills, you can use the Onyxia Scale Cloak to also obtain the
Blazing Shadowflame Cinder in Zaralek Caverns before swapping it out.Be careful not to accidentally sell or replace the Onyxia Scale Cloak before finishing both kills — if you do, item restoration is available through the in-game support system.