Frank Daniels wrote:
* use Total Defense while you're not under attack? E.g., you anticipate that you might be under attack at some point. Alternatively, maybe you just want to walk around with Total Defense "on".
This is a bit tricky in practice. The issue is that you don't get Dodge bonuses to AC (like total defence) when you don't get Dex to AC. There are two common causes for this:
1) An enemy you didn't know was there. Stealth, Darkness, Invisibility etc; if you don't see them coming, no AC bonus.
2) Flat-footed at the beginning of combat. Until you've taken an action in combat, you're flat-footed and don't gain Dex to AC.
#2 is the tricky one, because many GMs will not let you get the jump on a combat by always being in full defence, always having a readied action, or even always having your weapons already drawn. The pros and cons of that are varied, but basically: expect table variation.
What about in certain context sensitive situations? Such as right before turning a specific corner, or before someone opens a door?
Or would all of this be covered under readied action? As in, "I ready an action to use total defense if there is anyone/thing on the other side of that door"
Obviously, you can't go through the whole dungeon like this, but you could at least be prepared at key gateways and choke points.