File Location: ..server..//resource/scripts/ai/ai_define.lua
Find variable: "ai_flag_nohide"
Add in your monster anywhere, with a defining tag.
>> Eg.
ai_flag_nohide [YOUR_MOB_ID] = 1 (true) -- Label Your Mob Here (You won't regret it!)
Save it, restart gameserver, and tada the mob will reveal stealth.
Credits: Jones