First at all, I have to thanks Narshin the cleric in the reaver raid (at Ghallanda) point it out for me.
After a couple of test in game, I can now say the Holy Aura (CLR8) was not that useless in the main time.
Originally Posted by DDO In-Game description
Yes, pretty useless isn't it? Since these days, everybody and their dog at level 16, have a deflection bonus +5 AC item, or at least, can use +4 AC from shiled of faith, so the AC bonus from Holy Aura was next to useless.
Enchantment spell and charm spell? very rare monster in DDO cast such kind of spell, maybe just few vampire do so. And they LOVE to spam dispellOh well.
Now, +4 resistance bonus ... since Nightshield give up to +3 resistance bonus, and +4 item was almost everywhere, +5 can be a little bit tricky but that's not the point here. Again, useless, IF IT REALLY GIVE RESISTANCE BONUS to save.
Actaully, it isn't, in DDO.
Let's talk about Protection From Evil first; it suppose to give resistance bonuses on save against evil being, but IF IT DO SO, no one will bother to use it past level 9. So the dev decide to shift the resistance bonus to something else, let's say alignment bonus. It doesn't show up on your character sheet, but if any evil being casting spell on you, you can notice it on the combat log.
If you have the rule set from SRD, you could easily notice something interesting at Holy Aura section:
Now something is much more interesting -- if you cast Holy Aura in DDO, it DOES give you +4 *something* bonuses on your save, and you can easily notice it on your character sheet (unlike Protection from Evil). However, it doesn't stack with Protection From Evil's *alignment bonus* when you against evil being, so it's safe to assume that it also use the same bonus type on save as what protection from evil does. And it works for ALL Type of thing not just evil beings. Neutral target, Good target, even Trap !Originally Posted by SRD: Holy Aura section
So there's one more reason to use this spell, especially when you are in the situation which you want to boost your save.