Thunderherd Migration is a uncommon Sorcery card from The Lost Caverns of Ixalan Commander (LCC), collector number 259. Current market price: $0.33, TCGplayer market prices via Scryfall.
As an additional cost to cast this spell, reveal a Dinosaur card from your hand or pay {1}. Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.