The snowball (not entirely sure about the name) - uncommon

[mystic flame]

After 5 cards are scored in a hand, 1.25x mult for each card scored afterwards
Rewards effective usage with jokers like hack and hanging chad

Also a good early game option if u don’t have a lot of enchanted cards

I just realised an extreme version of this probably already exists in cryptid

[celest yoke]

Highly dependand on other jokers to do something (which is rare in vanilla Balatro) and with a Chad this is basically a x1.5 while uncommon.

[white echo]

multiplicative or additive

[mystic flame]

Multiplicative

[worthy dome]

i second getaro

[grim mural]

Para and showmen also. But those have better synergy with other jokers.

[celest yoke]

Para is famously the only one needing other jokers.
Showman's effect is not limited to jokers nor depends it on jokers.

[grim mural]

read the second part of the messages

[celest yoke]

read my message

[grim mural]

i read the message wrong. my bad bro

and i read "read" as read instead of read, and i had to reread read as read and not read