Spells which you conceal from your opponents are more devastating.
Benefit: When you apply the Invisible Spell, Silent Spell, or Still Spell feat to a spell you cast which deals hit point damage, you may add your sneak attack damage to the damage dealt by the spell. If the spell allows a saving throw to negate or reduce the damage, the sneak attack damage is also affected. The damage is of the same type as that dealt by the spell. You may use this effect a number of times per day equal to your Intelligence modifier.
Special: Using the tricky spells class feature does activate this effect. However, this effect does not stack with the surprise spells class feature.
Undefeatable: The Collected Feats Sourcebook, Copyright 2009 – 2010, Louis Porter Jr. Design, Inc. Undefeated, Copyright 2011, Louis Porter Jr. Design, Inc.