Hey guys,
I'm theorycrafting a character that is using the Transmutation subschool of Enchantment's Augment ability.
"Augment (Sp): As a standard action, you can touch a creature and grant it either a +2 enhancement bonus to a single ability score of your choice or a +1 bonus to natural armor that stacks with any natural armor the creature might possess. At 10th level, the enhancement bonus to one ability score increases to +4. The natural armor bonus increases by +1 for every five wizard levels you possess, to a maximum of +5 at 20th level. This augmentation lasts a number of rounds equal to 1/2 your wizard level (minimum 1 round). You can use this ability a number of times per day equal to 3 + your Intelligence modifier."
So my question is whether or not the Natural Armor bonus is an Enchantment bonus or an untyped bonus.
It doesn't say it's an enhancement bonus, just that it is a natural armor bonus with special rules that allows it to stack with other natural armor. So the answer to your question seems to be "neither." For all intents and purposes calling it untyped would work.
It's like the Dragon Disciple's natural armor boost. It will stack with anything.