Teardown

It's the capability to get your Buildings down one level at the expense of some resorces, so you can get that extra field back, each Teardown cost a percent on the building itself, that is 33,33%. So if the building costed 100 ore 100 cristal 100 hydrogen it will cost 33,33% of the total value, which is 33 ore 33 cristal 33 hydrogen.