I feel the same as you. WAR and MNK are the most difficult classes to play for me since they have more combos to fully unlock their potiential. If you are playing war I think what you need to do is to learn the fight then try to adjust your rotation based on your role in the fight. For example, if I am main tanking, I would focus on hate and defince rotations. If I am a dps I would focus on rotation to max my dps. Once you are experinced enough you can mix between rotation.