Golem

He was the one with the most observation type skills. And out of the skills, Eye of the Sky was the most special skill. And as it had a broad spectrum of uses, he used it extensively.

Muyoung found out about this skill through the assassination of Golem. The process took a good 6 months. It because Golem avoided all the traps and stakeouts to protect himself. Muyoung remembered that he wasn’t very powerful but he was very particular.