Hecatia has no AI so you have to manually use all 3 of her abilities, but once you use them all a few times, you'll have 3 planets rotating around where you targeted them. They stun, knockback, and do pretty good damage, and they're all Pure damage. She works pretty well in Pure damage decks, and is a good camera holder (if you think Kaguya camera is too cheesy)
Junko does a lot of magic damage, basically.

They should add card ability introductions in deck building time.