when you eventually get Saki and Spica, AW spirit is pretty much everything you need DC for so it's not that expensive, also like slyyr said, you need Gold and CC'ed silver unit for that, which isn't always ready to come by.And you should also look up at AW guides so you can find a way to fit your own style.

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In DMM they have a daily that drops it, but you can only deploy AW units
https://www.youtube.com/watch?v=RNw0eyzEPP8