So, I'm dealing with this ability and have some questions. Interested in popular opinion.
Master’s Illusion (Sp): At 8th level, you can create an illusion that hides the appearance of yourself and any number of allies within 30 feet for 1 round per cleric level. This ability otherwise functions like the spell veil. The save DC to disbelieve this effect is equal to 10 + 1/2 your cleric level + your Wisdom modifier. The rounds do not need to be consecutive.
So, "hides the appearance" made me think this was some form of invisibility, but it "otherwise" functions like the spell veil.
You instantly change the appearance of the subjects and then maintain that appearance for the spell's duration. You can make the subjects appear to be anything you wish. The subjects look, feel, and smell just like the creatures the spell makes them resemble. Affected creatures resume their normal appearances if slain. You must succeed on a Disguise check to duplicate the appearance of a specific individual. This spell gives you a +10 bonus on the check.
So, I guess it's some form of disguise? Which is disappointing considering the duration, but it made me think. What if I took the appearance of something that's naturally invisible like an invisible stalker or an aether elemental? Or barring that, what if I took the appearance of something very small, like an ant?
I think the problem is, if something is invisible then it doesn't have an appearance you can copy. A DM may be willing to allow it to duplicate invisibility because it's replicating such a high level spell. But, I think the RAI is that you can't use it to make yourself invisible.
I feel like the point of the ability is to use it when you're being chased. You and your allies turn down an alley way and then you all become innocent bystanders of some sort while the things chasing you run past.
As with most illusion magic YMMV depending on how your DM runs things. By RAW I don't see any reason you couldn't try to make yourself and your allies look like normal ants and any creature interacting with the "ants" (possibly from trying to walk through and/or occupying the space they're in) would get a save to see through the illusion.
Interestingly, since it's not invisibility it wouldn't use the normal invisibility rules. So the "ants" could still attack enemies and it wouldn't break the effect.