Knight of the Mists

Oracle Text

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)

When Knight of the Mists enters the battlefield, you may pay U. If you don't, destroy target Knight and it can't be regenerated.

Card Rulings

10/4/2004 If no other Knights are on the battlefield, pay the mana or destroy this card.
10/4/2004 Can destroy an opponent’s knight.