Masteria Preview?

I always though every "exclusive content" was programmed and prepared by the company related to the zone but under nexonkr supervision

also who made this firetusk sketch? or it was some joke? because I cant find any info about it(even the image itself is dead) and it was on the thread I've posted

That's an early sketch by NxProse, if I'm not mistaken.

And no, it's not always the case. For example, Amoria was dev'd in Korea. NexAM doesn't actually have enough (or possibly any) MapleStory developers. Back when Prose was around, I thought there were a few. But they don't seem to be around anymore. They do have developers for their social games (Facebook), though.