Self-mill means youre targeting yourself and your own library, so its cards from your library going to your graveyard
Play it alongside some +1/+1 counter synergy like Innkeeper's Talent or Hardened Scales to maximize its value
Depending on the format, you can use your trusty turn-1 Llanowar Elves to set up your future plays, or you can use cards like Elvish Archdruid and Priest of Titania to produce tons of green mana depending on the number of elves you have on the battlefield
In Tempest, it was turn one (Mogg Fanatics, shadow creatures, and flyers), Invasion turn two (2/2 bears for every possible color combination plus several one- and two-mana apprentices and utility creatures), and Mirage turn three
All of these cards continue to see adequate play in formats ranging from Modern to Vintage
It would be like printing a Samurai deck