Rules: Using a Tower Shield as Total Cover and Overrun

[harmor]

How does using a Tower Shield as total covert work with Overrun?

[harmor]

Nevermind, you can't overrun and use a Tower Shield as Cover at the same time because they are both Standard actions.

However, you can Tumble (provided you are carrying a light load or are not hampered by speed), but you can't change the facing so they simply attack you from behind.