Mr Khan, have you the rahian armor ? you should if not the case. Bring some firedouse berry also fo added fire protection, and furthermore add some fire decoration aswell for a 35 fire protection on your rathian armor.
For the first run, bring capture materials, I found out he was pretty hard to fight till the end. you need to capture him to end quickly the mission, he enters in rage mode and changes location a lot when he is about to die.
I used a long sword against him, ideally a dragon one (leech some Jhen Mohran quest for this !), but with a good LS like a anahanta boneblade you'll be able to do sthg. Cut his tail as fast as possible, so his annoying sweep tail will be less effective. Consider the bombs as well when he fells. A L bomb plus a small/felyne is very useful.
Good Hunt !
