In this way, you can get these cards as often, in total, as you can get cards that are only available in a single treatment
Each source material card appears at the same rate
Of course this isnt really a new mechanic at all, just a reimplementation of the saga mechanic introduced with Dominaria (and later reintroduced with Theros: Beyond Death and Kaldheim)
You dont even necessarily need to have self-mill cards like Town Greeter, Shinra Reinforcements or Vanille, Cheerful lCie (though those should absolutely be prioritized)
I know, this isnt the flashiest card on this list, but it does a simple job and it does it well
Hoser cards Ethersworn Canonist is obviously great versus Storm decks, but its also useful against decks that want to play a ton of cheap spells in the early game (think things like Infect and Burn)