Mystical Teachings is a uncommon Instant card from Time Spiral Remastered (TSR), collector number 76. Current market price: $0.19 (foil $1.08), TCGplayer market prices via Scryfall.
Search your library for an instant card or a card with flash, reveal it, put it into your hand, then shuffle. Flashback {5}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)