Crushing Amethyst Burial

A dome made of amethyst forms around an area. Every turn it closes inwards, slowly crushing all things inside of it while vibrating at high levels. Can withstand 100 points of damage and heals each round. Rank: C. Style: Ninjutsu. Chakra cost: 30 per round. Range: 60ft cube centered within 100ft of the user. Save: 12, power for half dmg. Damage: 4d10 sonic per round. Focus: yes. Requirements: Two free hands. Enhancement: Doubled radius. Action