They cast two copies of The regenerate ability is still protecting the Deathdealer, so the first Heros Downfall resolves and the Deathdealer survives
The tokens created by the squad ability aren't "cast," so any abilities that trigger when a spell is cast won't trigger for the copies
The legendary human warrior getting banned didnt stop players from including Winota, Joiner of Forces in a variety of Commander decks, though
Unlike the Orzhov deck, this is a more midrange-y deck with a higher curve featuring seven 4-drops
Using it right after a Windfall where you force every player to discard and draw 20 cards is a surefire way to get ahead, but even if you only get three mana back, you'll get all the cast triggers from your permanents for free
Even though it doesnt have haste, like Mistcutter Hydra or Gaeas Revenge, its so big and robust of a threat, and for such an efficient cost, I would expect well see a lot of it