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The Real Dragon Emperor

Defeat the Rampaging Dragon Emperor, and take the soul crystal it drops to Xiao Ling.
 

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Introduction

The power within the crystal is incomprehensible. When defeated, the Dragon Emperor comes back in the form of a dragon.
The voice told Xiao Ling that the soul crystal can be destroyed using the Dagger of Antiquity.

NPC Dialog

Do you see this? This is the Dragon Emperor's true
form.
The voice told me that the Dagger of Antiquity can
be used to destroy this soul crystal, and destroy the
Dragon Emperor himself.
With this crystal, we have our only chance. If we
can't destroy it, the Dragon Emperor will soon revive
once again.

Quest Completion

It is time...
Dagger of Antiquity, please grant me the power to
destroy the Dragon Emperor for all eternity!