For the dustform, perhaps one of these more simplistic solutions can be adapted...
Unravel (Ex): Once per day as a standard action, a hangman golem can unravel its form to become a heap of tangled ropes that fills a 10-foot-by-10-foot area. While in this form, the rope golem cannot attack or move, but it gains fast healing 10. A hangman golem can reform into its humanoid appearance as a full-round action.
Boulder Defense (Ex): A thomil can change its shape to a smooth, immobile, boulderlike form. In this form, the thomil's damage reduction increases to 15/- and its spell resistance increases by 5, but it cannot move or make attacks. Assuming this form takes a standard action, while returning to its semihumanoid form is a free action.