What the Hell is Going On?

Ever since the first sign of battle from Brigitta and Orson, Rex has already activated the newly acquired skill that he got from surviving the trap set by the Supernaturals to kill him. Due to the situation, he has never gotten the chance to try the skill out.

King of Kings, that is the name of the skill. A powerful binding skill exclusive to him.

It's located at the end of the skill tree of the system after he reached the requirement to learn the skill, the requirements are becoming a King himself which is reaching the ninth-rank realm, and also experiencing a fight with multiple King-level entities.

But thanks to the sudden quest, the reward has given him this skill without the need for skill points.

Normally he would've needed to pay 100 skill points in order to learn the King of Kings skill, a hefty amount that he doesn't have. It would've taken him forever to accumulate that many skill points, and now he gain access to the skill.