Yeah, I can't really recommend Spica highly enough for anyone who lacks Nanaly, Minerva, Anelia or Rachel. Spica is admittedly a bit fragile but otherwise she's stupidly well-rounded thanks to her skill, elf stats and awakened ability. Eventually we'll reach a point where mixed defenses are common enough that Pirates really start to shine but until then Spica does an excellent job of hitting the sweet spot between attack rate, range and sheer power--when her skill is up she does just enough damage to start chewing through basic black heavy armors and red gargoyles yet she also attacks quickly enough that she can do a decent job of clearing out basic goblins too. Barring premium gacha there really aren't any units you should really be Awakening first on Nutaku. If nothing else she makes it easier to sleep walk your way through the Thursday daily.