Hyborias Fallen question


In reference to the Wastrel (thief/pirate class combination) variant rules option (page 122 Hyborias Fallen) “Greater Whole” ability

“The wastrel may total all the damage he deals against it in a single round”

Does all the damage dealt in one round add together to just one amount for the purposes of massive damage?

If more than one attack is subject to the sneak attack extra damage would they be added as well?

Is there any further explanation or examples to illustrate how this ability is used?
I don't have the book at hand, but IIRC it is for DR only. That is, you total all damage done in a round and only subtracts DR once, instead of subtracting DR for each and every attack.

This will most likely make a dual wielding dagger-stabbing thief able to hurt a guy in a plate :)