Omastar BREAK from XY10 Awakening of Psychic Kings / Fates Collide has been revealed by the official Japanese Pokemon Twitter account. Thanks goes to Jake C. and Bangiras for the translation!
Omastar BREAK retains the attacks, Abilities, Weakness, Resistance, and Retreat Cost of its previous Evolution.
Ability: Dangerous Tentacles
Once during your turn (before your attack), you may choose 1 of your opponent’s Benched Pokemon-EX and switch it with his or her Active Pokemon.
Helix Fossil -> Omanyte -> Omastar -> Omastar BREAK. Ouch.