Archery Training is a uncommon Enchantment — Aura card from Urza's Destiny (UDS), collector number 2. Current market price: $0.18 (foil $1.96), TCGplayer market prices via Scryfall.
Enchant creature At the beginning of your upkeep, you may put an arrow counter on this Aura. Enchanted creature has "{T}: This creature deals X damage to target attacking or blocking creature, where X is the number of arrow counters on Archery Training."