Hellspawned Grace

Warlock Invocation
Level: Greater, 6th lv
Components: V, S
Casting Time: 1 standard action
Range: Self
Duration: Instantaneous
Saving Throw: None
Spell Resistance: No

You take on the form and statistics of a hellcat for a number of rounds equal to 1/2 your warlock level. This is a polymorph effect.
If reduced to 0 or fewer hit points while in hellcat form, you can't use this invocation again for 1 hour.

(Complete Mage, Page 124)