What are these skillbooks in Cash Shop?

I came back to gMS to try Evan a bit, but when I entered CS I noticed that there where skillbooks selling. Magic Critical and Magic Guard.

Are they helpfull for my Evan? Are the skillbooks when used time limited? and how do they work?

Normal skill books, except you have to buy them. Magic Guard is kind of useful for, you know, not dying.

I know, so I actually need to buy the skillbook in CS. No way to get it in game?

I don't think there is. When NexonKO did this with Dual Bladers, there was. Well, it was glitched but they said there was. NexonNA is special though.

Apparently they drop from a boss that nobody knows.

Apparently they drop from a boss that nobody knows.

I seriously doubt it.
It's pathetic too that even Hime goes on and apologizes about it not being out and they would get on it yet it never happened.

Really? Last I saw she said she was mistaken and it was intentional and maybe they'd release them later. eventually. some day. SUCKER.

Nexon's wonderfully sneaky way to make a class pay2play...