Simple enough. As long as Sam Fisher can find a secluded dark area that would render him invisible, he can set up Sticky Cameras to get a panaramic view of all the entry points for Paine. This way he can know where she is at all time, thus leaving him virtually invulnerable to Magic. Once the right time happens, he can Sticky Shocker or Air Foil her for the stun, then simply Sniper Rifle her face into oblivion.

The smooth walking "ghost" can easily use this arena to his advantage and take her out without her even realizing what hit her.

Another scenario. Use the Sticky Camera to get her in sight, then Shoot a Diversion Camera to either (1) Smoke screen her in, then stun, then facial, or (2) get her turned the other way, then stun, then facial. Either way, Sam is a veteran of invisibility and will take this battle.