"You have a 6% chance to hit your target with a Lightning Shield Orb charge when you do damage, and increases your spell damage by 3% when you have Lightning Shield active." (rank 3)
Source:
http://urlshort.com/wotlk/site/views...?spellid=51527
From the
http://urlshort.com/wotlk/site/talentlist.php site.