While cards with very wide ranges of performance can be fine you ideally don't want them to be your answers
Look for packs on sets that are a few months old : Some of the sets released last year (like Wilds of Eldraine, Phyrexia All Will Be One, and The Brothers War to name a few) are getting super cheap
Out of all of them, Doubling Season is going to be the most powerful, and, as you probably guessed, also the most expensive
Let me know in the comments below or over in the Draftsim Discord, and check out The Daily Upkeep newsletter to stay up to date on the latest MTG news
Five theme decks were released as part of the set
But raising the floor of an effect thats already got a good ceiling is always important and its always a great flex when you find ways to use a card that your opponents hadnt even considered