There are a few things you should keep in mind though
There are a few different ways to bring this Emrakul into play well before you have twelve mana available to you
Number 23 Language English Legal Formats Commander, Legacy, Pauper, Vintage Not Legal Formats Alchemy, Brawl, Competitive Brawl, Historic, Pioneer, Standard, Timeless Rulings (12/8/2022) You choose the target for Dread Return before paying any of its costs, so it's not possible to cast it using flashback and bring back one of the creatures you sacrifice
The reality, for better or worse, is much simpler: the cards we get are decided in advance
However, for just one more mana you get lifelink and it forces a discard when it attacks
Often times the one weakness is too much synergy between the block, and almost none in Chaos draft