This is the same concept as the boss MeteorDoves. The "DB Devil" is called WaterDevil and looks exactly like all the other water devils. However, it has much higher defense so you do less damage to it. And, it hits a lot harder than the others. It spawns once each day in one of the locations on the provided map.
@ahmedamin889: Yes, every time you kill it you are guaranteed to get a DB.
I have a lvl 122 rb tao with 407 m-def, way more than Bigdan2k5's 289 m-def. However, that devil hits me for 1624 not the 200 he got hit for. And ken_L (likely a warrior given that he used SM) took 200 damage or so. So I think it's physical attack or it wouldn't hurt me so much, given the damage reported by others.
One final thing, yes you can have edited maps that show in game. It's been done already...check this thread by
malisto:
If you'd like to edit them further, the in-game map for this region is divided into 4 files in his map collection. Unzip archive and put everything into data/minimap folder. The files pertaining to this region are:
map1212a.jpg, map1212b.jpg, map1212c.jpg, and map1212d.jpg
Good luck hunting it!