help

[v1k1ng]

the feat dodge provides me +1 AC for attacks of opportunity, and the feat mobility +4, and spring attack negates those attacks entirely. is this +1 and +4 AC bonus always active or only in case of an attack of opportunity?

if not, wouldnt it be better to raise the tumble skill to high levels and gain +1 effective (=not only for attacks of opportunity) AC bonus every 10 levels of tumble?

[Lobo13]

V1k1ng, it is really two separate things.
Tumble gives you the AC automatically, all the time. And it is a good skill to have.
The other two kick in only during those specific attacks on you. Which is handy if the enemy sneaks a hit in, on you. Those bonuses come in handy when fighting more than one foe, which is often. It kind of protects you when you are concentrating on one enemy and the other(s) attack from the side. If there is one foe, then the effects stack.

In pen and paper DnD, tumbling would be a die roll to see if the first attack against you succeeded, and the dodge would be rolled to see if the second foe succeeded in attacking you. Mobility is along those same lines.
Parry would be rolled to see if you could counterattack the same round.

I hope that answers your question.

PS I reserve the right to be wrong.