Penetrate Ability in Book 8 Mini-Adventure

[Moonreaver]

Is there any limitation on the Penetrate ability in the Book 8 Mini-Adventure? Nothing is mentioned in the ability's description but doing an extra 4 points of damage in combat any time you want seems overpowered compared to the rest of the abilities.

 

[beowuuf]

I think the equivalent damage is spread over three combat round once, so imagine it is a once only ability

 

[The Wolf]

Yep, what beo said. Might not have been worded as well.