Wild Shape (Su)
Source: Advanced Player's Guide, p. 100
A mountain druid gains this ability at 6th level, except that her effective druid level for the ability is equal to her druid level – 2. A mountain druid cannot use wild shape to adopt a plant form. However, at 12th level she can assume the form of a Large giant as if using giant form I. At 16th level, she may assume the form of a Huge giant as if using giant form II.