Empress Defeated (in kMST)

From the pserver I dabled with a month ago, it was killable and there was a notice once you killed it. It was pretty much a mirror of the real server except two modded npc's that distributed NX through voting.

There's no such thing as a "mirror of the real server" unless you're implying Nexon's server sources have been leaked (recently).

Everything that is server side, including drop, boss behavior, "anti-hack" measures such as hidden drop conditions or map kickout, death notices, death buffs, and so on, is rewritten in the private servers.