Lin Huang visualized the Death Butterfly from the Coffin Carrier's God Figurine which was an Abyssal Protoss. Since there were quite a number of True Spirits that mastered the Death Rule, Lin Huang was having a hard time choosing which to visualize.
Eventually, he chose the Death Butterfly which combat ability was relatively weak because it guarded the Yin Yang Gate. It could travel between the material realm and the spirit realm when it reached true god-level.
Lin Huang did not know much about the spirit realm. He only knew that it should be the place spirits went to after they died.
Naturally, he had no idea what the death spirit energy Grandmistress Wei was talking about was at all. He could not help but ask the stone tablet when he heard Grandmistress Wei mention it, "What exactly is that death spirit energy she was talking about?"