Riftmarked Knight

Protection from black; flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
Suspend 3—{1}{W}{W}
When the last time counter is removed from this card while it's exiled, create a 2/2 black Knight creature token with flanking, protection from white, and haste.

Plains

Mtenda Herder

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

Outrider en-Kor

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
{0}: The next 1 damage that would be dealt to this creature this turn is dealt to target creature you control instead.

Knight of Valor

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
{1}{W}: Each creature without flanking blocking this creature gets -1/-1 until end of turn. Activate only once each turn.

Knight of Sursi

Flying; flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
Suspend 3—{W} (Rather than cast this card from your hand, you may pay {W} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost. It has haste.)

Femeref Knight

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
{W}: This creature gains vigilance until end of turn.

Citadel Gate

This land enters tapped.
As this land enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Zhalfirin Commander

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.

Knight of the Holy Nimbus

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
If this creature would be destroyed, regenerate it. (Tap it, remove it from combat, and heal all damage on it.)
{2}: This creature can't be regenerated this turn. Only your opponents may activate this ability.

Gustcloak Cavalier

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
Whenever this creature attacks, you may tap target creature.
Whenever this creature becomes blocked, you may untap this creature and remove it from combat.

Cavalry Master

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
Other creatures you control with flanking have flanking. (Each instance of flanking triggers separately.)