While not a planeswalker card, Modern Horizons 2 did print Garth One-Eye as a legendary creature
Then when it ETBs, you draw cards equal to your creature count, for just one more mana than Collective Unconscious
Requiring no activation cost other than tap, the Library combines amazingly well with other card-drawing effects that put seven cards into your hand, including Wheel of Fortune, Timetwister, and Time Spiral
The mono-black artifacts theme has been eclipsed by the Necron cards from the Universes Beyond: Warhammer 40,000 Commander decks, but these two are the original evil artifacts build
Drawing cards is always good and it quickly becomes the best card on the board when it turns into an effect that draws three, four, or 10 cards each turn