That was the pattern formed by the intertwining transformations of Lin Chuan's three Mangekyō Sharingan—a Mangekyō Sharingan pattern unique to him.
Faced with the Supreme One Sacred Ancestor's relentless pressure, Lin Chuan had reached the point where he had no choice but to reveal his trump card. This battle would determine the life or death of both him and Konoha.
The Supreme One Sacred Ancestor also noticed the change in the patterns within Lin Chuan's eyes, but it did not matter to him. He did not believe Lin Chuan could withstand his attack.
Before making his move, what he had feared most was not Lin Chuan fighting him, but Lin Chuan immediately using that strange spatial technique to flee. If that happened, he truly had few ways to deal with Lin Chuan—at most, he could destroy Konoha to vent his anger.
That was also why he had shattered Konoha's city-protecting formation the moment he arrived. He wanted everyone exposed to danger, forcing Lin Chuan to make a choice.
If Lin Chuan fled, Konoha would be destroyed. All the cultivators of Longevity Heaven would see a selfish, shameless Naruto who did not care whether his subordinates lived or died. Even if Lin Chuan escaped, his reputation would be utterly ruined. No one would trust him again, nor would anyone stand by his side and fight alongside him.
That way, even if Lin Chuan escaped, he would be unable to stir up much trouble again. It would at least make up for the loss of failing to kill him.
But if Lin Chuan did not flee and chose to confront Supreme One Siming head-on, that would be the best possible outcome for the Supreme One Clan. They would seize this chance to kill Lin Chuan at any cost and eliminate all future