Go with long range water/earth, your enu will be doing okish dmg but it will boost the dmg output of the iop by around 50% due to the -200 resist shredding.
Another thing you could focus your enu to do is MP removal so that mobs will stay glued to the feca or the iop, this way your main dmg dealer wont have to run too far to deal dmg.
If you are going ranges you could consider fire branch also. You cant specialize single target but you can shred multiple enemy resistances at the same time.
I'm still confused on how to build my enutrof, if I go CC he doesn't have any skill to get close to the target and if I go range when he turns drhellzerker if I build range I'll probably have low resistance.
Another thing you could focus your enu to do is MP removal so that mobs will stay glued to the feca or the iop, this way your main dmg dealer wont have to run too far to deal dmg.