Best way to check combo is to do:
1st: sword skill
2nd: ragefull blow
3rd: twisting slash
*try this on mobs, I suggest devias 2. (This was my technique during my early days here to check if my combo is working then practive on PVP)
Remember to do marlon's quest and make sure to complete it, when you reset your character you have to do marlon's quest all over again.