... ok i found a bug... if you move ur note cursor all the way to the bottom of the game screen, the grey clamp like things that crashes together cannot tell, therefore, they do not attack, however. when the cannons come in, if the cannons hit the bottom of the game, u lose a life.
It's so easy to farm soul ._. beat level one and keep repeating it until you reach 130 soul. Then upgrade the weapon you want. Once you upgrade once, suicide and when you retry, u keep the upgrade but have 130 soul again. Just keep doing that and u can upgrade your weapon to the max :D