If you want the Mewtwo V SA specifically, buying the single at ~$85120 is far cheaper than chasing through boxes (estimated ~25 boxes for a specific SA pull)
Reward: Mabosstiff Emblem Fantastical Parade secret missions Fantastical Parade Museum 1 How to beat: Collect every One-Star full art variant card in Fantastical Parade: Cacnea, Roserade, Vivillon, Buzzwole, Reshiram, Oricorio, Scorbunny, Aurorus, Cramorant, Minun, Toxel, Galarian Ponyta, Snubbull, Indeedee, Sandshrew, Tyrantrum, Falinks, Alolan Muk, Purrloin, Yveltal, Galarian Obstagoon, Galarian Perrserker, Salamence and Slakoth
Sacrifice is as strong as it is because of the added value you get from so many sacrifice triggers
The quality of the cards is also higher than what it was, with some collectors even placing the present-day Korean cards above the US and Japanese equivalent cards in terms of quality