Proportionate Wild Shape
( Masters of the Wild: A Guidebook to Barbarians, Druids, and Rangers, p. 24)[Wild]
You use wild shape to become animals of your own size, even if your wild shape ability would normally exclude that size category.
Prerequisite
Ability to use wild shape, natural form neither Small or Medium-size,
Benefit
You use your wild shape ability to take the form of an animal whose normal size category matches your own. For example, a cloud giant druid (size Huge) with this feat could use wild shape to become a Huge shark or a giant squid.
Normal
The size of the animal form you can assume through wild shape is limited by the parameters of the ability, regardless of your original size.