Attunement

Before you can enter Onyxia's chamber and even attempt to defeat her, you must complete an epic series of quests to get a key. The key is in fact an amulet that "attunes" you to the instance and allows entry to her lair. The quest chain for Horde and Alliance races are very different.

The amulet that you are seeking is the Drakefire Amulet. It provides two key things for the Onyxia chain: It acts as the key to the instance and it provides some fire resistance.

You can find our Horde guide to becoming attuned here: Horde Onyxia Attunement Quest Chain

You can find our Alliance guide to becoming attuned here:Alliance Onyxia Attunement Quest Chain

Onyxia's Lair

Once you have become attuned to the Onyxia instance it is time to gather your friends and attempt to destroy the beast in her lair.