Okay, I have a couple of design questions for the Woad.
He is intended to be touched by magic, Terram aspected specificically. He also intends to do battle in the front lines. There are a number of ways to avoid getting killed.
I don't want a Rego Terram ward against weapons. Although I see the saga has HRs for this solution to ogger improves soak rather than total immunity. I like that, bit it's not my vision of the Woad.
RoP:Magic offers some solutions. Obviously I'll take Magic Blood for the backgrund. Being a Magic Thing (rock) grants a Lesser Power. Since the effect I'm gunning for is a Skin of Stone effect, which affects only himself this might as well be a Personal Power. Some of the levels should be spent to reduce the cost, which is in Fatigue rather than Might, because he has no Might. It could be even better if taken as a Greater Power, costing a Major Virtue. Another question is the design of this: Skin of Stone should not turn him into a statue, he needs to be able to move, but should look unnatural. I'd rather have a Soak bonus than total immunity. MuCo(Te) Base 25 transforms a human body into stone, but is this an immobile status? Base 30 turns into water or air, but these example spells allows movement.
Another solution is to take Essential Trait, which can give a +3 or +6 speciality bonus to a characteristic, here specifically bonus to Soak.
Yet another solution used not RoP:M but core rules only. Simplest and smallest is Touch. Larger is Greater Immunity (Iron weapons). But I'd rather have an unnatural, sometimes-on power than a discreet, sometimes-on virtue. It fits the character better.
And I certainly don't want the aforementioned effects or powers to stack. I just want some durability for the fighting style the Woad employs.