Butcher hero: hook'n'chew RPG

I'm trying to destroy the crystal on Island 9, but it seems like they counter-attack and heal, making it really hard to break through. If anyone else is doing this, I'd appreciate some advice.

このゲームやってるひといる？ 説明もなにもないけどなんとなくでできる イベントに夢中になりすぎると時間を忘れて寝不足になるから注意！