End of the mission

Once Chris started his attacks, there was nothing those spies could do to escape the attacks. His INT was so high that he could cast those spells without a break and almost instantly too.

With his high INT, Chris wouldn't take much time to cast a spell/skill. If anyone sees his casting, they would think that he has [Instacast] and or [Silent Cast] skills along with the [Multicast] skill.

These skills are something that are in high demand. Unlike other spells or skills, these aren't easily obtainable. It would take decades to get to a state where you can able to execute these skills properly, without using a skill book.

Indeed many powerful mages would try to get their hands on the skill books rather than slowly practice and perfect them. It takes a lot of time and Time is Money. They can't waste the most precious resource that can't be regained, time.