SM,

When you pick IF, you are looking at two things.

1.) You have no combat mages to speak of. Even if you get lucky, they are going to be piss poor and cost alot to invest them to make them so.

2.) You are playing standard Ulm but trying ot maximize a blessing effect. Like Alex said, the only reason to take IF is for the Bless effects otherwise Base Ulm is far superior.

A rainbow is counterproductive to bless effects. I don't know if I'd pick earth either, since it's bless effect really doesn't shine until 9 unless you have combat mages. Reinvigoration on heavy and expensive templar doesn't do as much for me as say, Berserk, or +Att and Flaming weapons.

I have been in the middle of a game so I haven't really had time to respond I'll have more time for an in depth response a little later.