More specifically, I'm building a Wizard and I'd like him to have the Perfect Body, Flawless Mind capstone (+8 Int).
I'm planning for him to be a diviner, specialized: Foresight, with the Pact Wizard (HH) archetype (that, as far I can tell, does not replace a wizard's capstone, since a wizard does not have one to begin with), and wonder if it'd still be legal to get the alternative capstone.
Does the natural 20 from Forewarned (Divination school) count as a capstone?
At 20th level, anytime you roll initiative, assume the roll resulted in a natural 20.
If so, am I able to select the alternative capstone in its place (since it's not an archetype)?
If not, could I do it as an universalist?
Alternative Capstone Ability
When a character reaches the 20th level of a class, she gains a powerful class feature or ability, sometimes referred to as a capstone. When a character reaches 20th level in this class, the following new ability can be selected instead of the standard 20th level class ability which would normally be gained. In some cases, a capstone specifies what ability it replaces. A character can’t select an alternative capstone if she has previously traded away her class capstone via an archetype. Clerics and wizards can receive a capstone at 20th level, despite not having one to begin with.