Flusterstorm
Instant
Counter target instant or sorcery spell unless its controller pays 
.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)
Erica Yang
Vintage Masters (VMA)
• #68Rulings
Spells cast from zones other than a player's hand and spells that were countered are counted by the storm ability.
(wotc • 2022-12-08)
The triggered ability that creates the copies can itself be countered by anything that can counter a triggered ability. If it is countered, no copies will be put onto the stack.
(wotc • 2022-12-08)
You may choose new targets for any of the copies. You can make different choices for each copy.
(wotc • 2022-12-08)
A copy of a spell can be countered like any other spell, but it must be countered individually. Countering a spell with storm won't affect the copies.
(wotc • 2022-12-08)
The copies are put directly onto the stack. They aren't cast and won't be counted by other spells with storm cast later in the turn.
(wotc • 2022-12-08)
Rulings
Spells cast from zones other than a player's hand and spells that were countered are counted by the storm ability.
(wotc • 2022-12-08)
The triggered ability that creates the copies can itself be countered by anything that can counter a triggered ability. If it is countered, no copies will be put onto the stack.
(wotc • 2022-12-08)
You may choose new targets for any of the copies. You can make different choices for each copy.
(wotc • 2022-12-08)
A copy of a spell can be countered like any other spell, but it must be countered individually. Countering a spell with storm won't affect the copies.
(wotc • 2022-12-08)
The copies are put directly onto the stack. They aren't cast and won't be counted by other spells with storm cast later in the turn.
(wotc • 2022-12-08)