Excelsior

I was fighting with this monster and suddenly he just dissapeared im , stuck in the room and i dont want to lose my gaunt. It took me so many time to gather the bone and kill the bone demon

you mean shadow knight? if you do, it is normal that he HIDES when his hp is at half.. 1k of his 2k. you must reveal him, the best way to do it is use weapon with bleed attack and hurt him by it when it has about 1020 hp the blood will show you spot where is it , then you have just to cast reveal spell or use your detecting hidden skill....

oh thx since i have no bleed attack i will raise detect hidden and try to reveal him

hehe...... There is a cheating way to get him when he hides......
tame a low end pet ....and tell it to FOLLOW him..... Make sure it does NOT target him....
In older versions of runuo it would not get attacked but it WOULD allow you to track him..... I believe this also worked on OSI...But can't prove this...

Not sure if this still works....
I would have expected it to have been plugged by now... But worth a try!

Im almost gm detect hidden took me almost 1 hour not too bad , i will reveal him and kill him , i still hope i will get an arti for all this work