Zhalfirin Commander is a special Creature — Human Knight card from Time Spiral Timeshifted (TSB), collector number 18. Current market price: $0.19 (foil $0.32), TCGplayer market prices via Scryfall.
Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.) {1}{W}{W}: Target Knight creature gets +1/+1 until end of turn.