Sunstrike Legionnaire is a rare Creature — Human Soldier card from Legions (LGN), collector number 22. Current market price: $1.18 (foil $8.40), TCGplayer market prices via Scryfall.
This creature doesn't untap during your untap step. Whenever another creature enters, untap this creature. {T}: Tap target creature with mana value 3 or less.