You can briefly see invisible and ethereal opponents.

<php>echo “<b>Prerequisites:</b>”;</php> Perception 14 ranks
<php>echo “<b>Benefit:</b>”;</php> As a swift action, you can attempt a DC 30 Perception check. If successful, you focus your vision so clearly that you effectively gain the effects of a see invisibility spell, except it can only be used to spot invisible and ethereal creatures up to 60 feet away. This clarity lasts until the beginning of your next turn.