Invocation Grade: Dark
Equivalent Spell Level: 6th
You can use greater invisibility as the spell, but you can target only yourself with the invocation. If your retributive invisibility is dispelled, a shock wave releases from your body in a 20-foot-radius burst. This shock wave deals 4d6 points of sonic damage to all creatures in the area and stuns them for 1 round (a Fortitude save halves the damage and negates the stunning effect).
Source: Complete Arcane, page 135.