Back when he first ventured into the Void Sea, he hadn't become a Void Dominator yet. During an encounter in the Deceitful Fog Sea, he met a struggling Void Divine Positioner. At that time, he accepted a Seven-Colored Divine Artifact from the other person and promised to avenge their enemy once he had enough confidence.
The enemy was also a Void Divine Positioner, ranked in the middle and lower tiers of the Star Abyss's twentieth layer.
Logically, to kill such a powerful being, a single Seven-Colored Divine Artifact as payment was far from enough.
But it was merely a small investment with a glimmer of hope; there was no expectation it would succeed.
Furthermore, for Lin Qing at that time, a Seven-Colored Divine Artifact was still very valuable.
Now, with his increased strength, Lin Qing roamed around the Void Sea. While planting a soul mark on the Main Star and the Void Star, he also fulfilled this commitment.