Classic Hardcore Onyxia's Lair Attunement

Yes, Onyxia’s Lair raid features an attunement that you have to complete in order to enter the raid. That changed in the Wrath of the Lich King update, but you still have to do it in WoW Classic and WoW Classic Hardcore. The attunement consists of a long and tedious quest chain. Not only may you find it boring if you’ve already completed it before, but certain encounters can also be rather dangerous for your hero in Hardcore.

Onyxya’s Lair attunement requires the completion of a separate long quest chain. The quests in question are so complex and feature so much unique roleplay that the developers even had to separate them between factions, with the attunements varying wildly between the Alliance and the Horde. The former start the quest by speaking with Helendis Riverhorn at Burning Steppes and the latter get it from Warlord Goretooth at Blackrock Spire.

Yes, you cannot enter the raid unless you’ve completed the necessary attunement. Despite the short length of the raid itself, the attunement quest is quite long and complex, requiring players to complete a large quest chain to enter the raid. You also have to battle some powerful enemies while completing this attunement, which can be especially nerve-wracking in Hardcore.

Attunements are not account wide and tied to the character you received them on. In that sense, if you die and lose your character on Hardcore server, you will lose an attunement and will have to get it again with a new character. However, as long as your character is alive, the attunement stays with you