Mazemind Tome is a rare Artifact — Book card from Core Set 2021 Promos (PM21), collector number 232p. Current market price: $0.65 (foil $0.89), TCGplayer market prices via Scryfall.
{T}, Put a page counter on this artifact: Scry 1. (Look at the top card of your library. You may put that card on the bottom.) {2}, {T}, Put a page counter on this artifact: Draw a card. When there are four or more page counters on this artifact, exile it. If you do, you gain 4 life.