Cheapest priced copy (Visions): $0.35 at Card Kingdom, near mint, their price list as of .
Knight of the Mists 
Creature — Human Knight · 2/2 · Common · Visions · #36
Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
When this creature enters, you may pay {U}. If you don't, destroy target Knight and it can't be regenerated.
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
2 printings · $0.35 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Visions | 36 | Common | $0.35 | — |
| World Championship Decks 1997 | pm36sb | Common | $0.35 | — |
2 rulings from Wizards of the Coast
- 4 October 2004Can destroy an opponent’s knight.
- 4 October 2004If no other Knights are on the battlefield, pay the mana or destroy this card.