Stormwing Entity — ruling 1

To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Stormwing Entity). The mana value of the spell remains unchanged, no matter what the total cost to cast it was.

Stormwing Entity — ruling 2

Stormwing Entity's cost reduction applies even if the instant or sorcery spell you cast was countered or didn't resolve.

Stormwing Entity — ruling 3

Stormwing Entity's cost reduction applies just once, no matter how many instant and sorcery spells you've cast this turn.

Stormwing Entity : règles, fonctionnement et interactions (MTG)

Stormwing Entity is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

This spell costs less to cast if you've cast an instant or sorcery spell this turn. Flying Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.) When this creature enters, scry 2.

How it works : Stormwing Entity

Original English text — Wizards of the Coast / Scryfall

#1June 23, 2020· Wizards of the Coast
To determine the total cost of a spell, start with the mana cost or alternative cost you're paying, add any cost increases, then apply any cost reductions (such as that of Stormwing Entity). The mana value of the spell remains unchanged, no matter what the total cost to cast it was.
No other card is named in this ruling.
#2June 23, 2020· Wizards of the Coast
Stormwing Entity's cost reduction applies even if the instant or sorcery spell you cast was countered or didn't resolve.
No other card is named in this ruling.
#3June 23, 2020· Wizards of the Coast
Stormwing Entity's cost reduction applies just once, no matter how many instant and sorcery spells you've cast this turn.
No other card is named in this ruling.