[verb (plain)] + からこそ [i-adj] + からこそ [na-adj] + だ + からこそ [noun] + だ + からこそ
からこそ is から with こそ on it: "precisely because", "it's because… that…". It singles the reason out as the real one. It attaches the way から does – the plain form, with だ after a noun or な-adjective.
から states a reason. からこそ argues for one: this reason and no other, often against what the listener might expect.
It's a claim the speaker stands behind, so it does not give a plain cause for something that went wrong.
からこそ often takes something that looks like a drawback and makes it the reason for something good.
These go beyond からこそ inside one sentence.
だからこそ opens a sentence and points back at the one before: "that is exactly why".
The sentence can end on からこそ when the reason is the news: 〜~のは.…からこそだ.