Each attack is only slightly improved, but it all adds up in the end.
Anyone curious in each person's attack, since it's hard to keep track of them near the end:
Cirno: Random icicles (and bubbles near end)
Letty: 5 way curved lasers
Daiyousei: Green spiral
Wriggle: Bug egg spiral
Mystia: Aimed shot with blue trail
Chen: Two bubbles with trails
Parsee: Aimed bubble with flower trail
Nazrin: Vertical purple arrowheads
Hina: Card shot spirals
Medicine: Slow aimed purple bubble
Aki Sisters: Randomish leaves
Yamame: Falling spiral
Kisume: Falling laser
Rumia: Criss-cross ring
And a redundant screenshot for no reason: