The game features four battleground cards to choose the level of difficulty that is right for the players and two preconstructed player decks that are designed specifically for this quest
Sliver Queen, Brood Mother, Urza, and Selenia round out the top five (according to Card Kingdom), though a good bit cheaper than the top two
In both cases you want to start looking for sets of matching cards that you can organize into patterns
Milling a permanent is descending, cards in the graveyard are ripe for collecting evidence or foraging its designed well enough to play in its Standard and Limited environments, but my Commander-focused brain shall look elsewhere for my squirrels
Other cheap (price-wise) examples would be Pilfer, Concealing Curtains // Revealing Eye, Dread Fugue, Distress, etc