Read this handbook:

http://www.minmaxboards.com/index.php?topic=2811

I especially like Tren form. Mmmm. Tren.

8 Natural Armor, 30 foot land speed, 40 foot swim speed, +4 hide, (+8 in rocky/subterranean), 2xclaw (1d4), 1xbite (1d4), and Multiattack!