You can pick and choose individual cards, or you can create specifically themed modules that you can swap out between games
Notably, the returned Rats don't need to be among the cards you milled, so if a powerful Rat gets removed, Ashcoat can easily get it back so long as you don't mind milling four cards (and that effect can play into graveyard synergies too)
Here were five of my favorites
Contents: 1 Collector Booster Sample Pack 1 100-card Deck with 10 New Cards 1 Deck Box 10 Double-sided Token Cards 1 Foil-etched Display Commander 1 Life Wheel 1 Strategy Insert 1 Reference Card Limit 12 per customer
Legendary Creature - Shapeshifter Noble Possibility Technician Whenever this creature or another Kavu you control enters, exile the top card of your library
Revised Edition, 1994: $7,198 Original dual lands are the stars here, from Underground Sea at the top to Savannah toward the bottom but still well into the hundreds