Wrangler of the Damned

• WOTC Official Reminder Textofficial rules
  Flash — You may cast this spell any time you could cast an instant.

• WWizards of the Coast2024-04-12
  Official Ruling
  At the beginning of your end step, Wrangler of the Damned’s last ability will check to see if you’ve cast a spell from your hand this turn. If you have, the ability won’t trigger at all. If the ability does trigger, it will check again as it tries to resolve. If you’ve cast a spell from your hand since the ability triggered, the ability won’t do anything.

Rulings via Scryfall