Your problem isn't you calculating damage on the collision method (though i think it's wrong); I think you problem is that the OneEyeSkillSlash collides with your ship through various frames, making your ship life decrease rapidly. So you have some options. - Destroy the OneEyeSkillSlash after a hit. - Make your OneEyeSkillSlash not be able to damage again the ship. - Make your ship invincible for a short time after being hit. - Implement some other mechanic.