Bismuth + Peridot is literally the strongest combo in this game.

[Sonikku]

Bismuth's Special (White) + Attack (Red) item increases LCK of the party members next to her, but it also seems to make non-LCK-based events more common too, like the badge effects that happen after you get a LUCKY hit.

What this means is, stuff like the Lucky Star badge, which has the chance to give you 1 star point after a LUCKY hit, will give you those star points more often.

Peridot has a move that does 20x attacks minimum, 25x maximum and has an upgrade that guarantees at least 5 lucky hits if you hit all 25 hits. If you also use the Shamrock badge and Lucky Crown, you can get Peridot up to some insane LCK levels, plus the extra "hidden LCK" stat, too. My highest so far is 133 LCK.

The gist of it is, you can get constant 25 LUCKY hits on Peridot's Ferrokinesis attack, and 9/10 of those will give you a star point back EVERY TIME THEY HIT.

I'm drowning in star points, someone call the ambulance.

(Image that exemplifies the combo)
https://i.imgur.com/FzGRNr5.png

[Blight]

This also applies with Amethyst's skill that grants a chance of a skill costing 0 points based on luck. Use Bismuth's luck skill and it's free real estate for repeated 0 point cost Ame skills.

[kidfirewantslove]

xd

[Glycell]

Amethyst became my perpetual whipping machine. I gave her the shamrock and lucky star. With a group of enemies 3+ she will just keep whipping and making stars to whip more. In the Black Hole area at this point the other characters are just there for ballast.

She ends most encounters before the enemies even get a turn.