Mosquito Guard is a common Creature — Kithkin Soldier card from Morningtide (MOR), collector number 18. Current market price: $0.07 (foil $0.56), TCGplayer market prices via Scryfall.
First strike Reinforce 1—{1}{W} ({1}{W}, Discard this card: Put a +1/+1 counter on target creature.)