Draconic Polymorph

Transmutation
Level: Sor/Wiz 5
Components: V
Casting Time: 1 standard action
Range: Personal
Target: You
Duration: 1 minute/level (D)

As polymorph, except as follows: The assumed form can have no more Hit Dice than you have, to a maximum of 20 Hit Dice. Your Strength and Constitution in the new form are above the average for the race or species into which you transform; your Strength is the average for the creature +8, and your Constitution is the average for the creature +2.