We need an element that can get through overpowered walls/armor, but doesn't just destroy everything on the screen, so it works just as well against normal buildings and stuff.

Here is my suggestion:

There should be an element that can pass through any non-solid particles, and it will break any solids that it passes through. However, it doesn't use pressure to break stuff, it just directly converts everything into its broken form. For elements without a broken form, you'll have to get creative.

http://pastebin.com/gndSNE9Q

The idea of this element is to be very powerful, but also pretty slow. It's meant to be really fun to use.