Myths Descend to the Heavens

There are two villains in history who are particularly evil. The first is Gargulas Gargulra. My impression is that after he took possession of the Dark Circle, he didn't wreak havoc on the city. But every time Uub comes out, he always comes out once or twice. In the Zeta plot, he seems to only appear once. The second one is Tregear, who was originally a warrior of the Kingdom of Light. Later, after his mentor Shikari fell into darkness. He began to tire of the Kingdom of Light. Then he seemed to fall into darkness for some reason. And then it seemed like he didn't really fall into darkness. In the Taiga plot, he seemed to appear two or three times. Then, I heard that he seems to be Taiga's teacher Tregear, who also has a heart of light and has not been eroded by darkness.