FIREIV is your nuke spell basically and should be used otherwise the dmg will be low. After practice you get the timing right were as enochian does not fall off. Sharpcast is also great to use. Aikaal has a great guide that your friend may find of interest. It is more complex but with practice it is ideally what a blm is looking at in terms of rotation for end game.
I also prefer to Use Thunder 1 over 2 and T3 is not at all used anymore (casting it i mean)
Also to note potency of thundercloud proc would take priority over say a FIREIV because of potency.
SS>Crit> other stats, at least that is what i prefer in hw atm