Elvish Harbinger is a uncommon Creature — Elf Druid card from Duel Decks Anthology: Elves vs. Goblins (EVG), collector number 4. Current market price: $6.61, TCGplayer market prices via Scryfall.
When this creature enters, you may search your library for an Elf card, reveal it, then shuffle and put that card on top. {T}: Add one mana of any color.
All Duel Decks Anthology: Elves vs. Goblins cards and prices