Many Mythic Paths in Mythic Paths of the Lost Spheres support multiclass characters but as of yet there aren’t many multi-path mechanics out there despite the Dual-Path feat. But the possibilities are endless for path interaction and one such option exists for a Master-of-Shapes that also know the suffering of the Hollow One:
For the Master-of-Shapes and Hollow One mythic paths from Mythic Paths of the Lost Spheres:
Form of the Taken (Mythic)
Your metamorphosis allows you to wear the shapes of those within you.
Prerequisites: Dual-Path feat, Enslave Supernature and Moment of Supernature path abilities.
Benefit: As a standard action you may expend a use of mythic power during a shapechange effect to assume the form of a possessing creature you have access to for the Enslave Supernature ability. For 1 round per tier you may fully manifest the creature as though possessing it with a marionette possession spell. You may use any extraordinary and supernatural abilities the creature has within normal usage limits. Spells and spell-like abilities are available if they are equal or less than your tier. If the creature “dies” during this period your are forced to resume your true form and are dazed for 1 round.
You can get Mythic Paths of the Lost Spheres on: RPGNow or Paizo or d20.pfsrd.com!
"Find the Hero Within" - Lost Spheres Publishing 