Gravel Slinger is a common Creature — Human Soldier card from Onslaught (ONS), collector number 33. Current market price: $0.08 (foil $0.53), TCGplayer market prices via Scryfall.
{T}: This creature deals 1 damage to target attacking or blocking creature. Morph {1}{W} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)