Rockshard Elemental is a rare Creature — Elemental card from Legions (LGN), collector number 109. Current market price: $0.31 (foil $2.74), TCGplayer market prices via Scryfall.
Double strike (This creature deals both first-strike and regular combat damage.) Morph {4}{R}{R} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)