Sun Droplet is a uncommon Artifact card from Mirrodin (MRD), collector number 249. Current market price: $0.46 (foil $8.48), TCGplayer market prices via Scryfall.
Whenever you're dealt damage, put that many charge counters on this artifact. At the beginning of each upkeep, you may remove a charge counter from this artifact. If you do, you gain 1 life.