Xerex Strobe-Knight

Flying, vigilance
{T}: Create a 2/2 white and blue Knight creature token with vigilance. Activate only if you've cast two or more spells this turn.

Swordsworn Cavalier

Swordsworn Cavalier has first strike as long as another Knight entered the battlefield under your control this turn.

Deserted Beach

Deserted Beach enters tapped unless you control two or more other lands.
{T}: Add {W} or {U}.

Zhalfirin Lancer

Whenever another Knight you control enters, Zhalfirin Lancer gets +1/+1 and gains vigilance until end of turn.

Knight of the New Coalition

Vigilance
When Knight of the New Coalition enters, create a 2/2 white and blue Knight creature token with vigilance.

Island

Plains

Knight-Errant of Eos

Convoke
When Knight-Errant of Eos enters, look at the top six cards of your library. You may reveal up to two creature cards with mana value X or less from among them, where X is the number of creatures that convoked Knight-Errant of Eos. Put the revealed cards into your hand, then shuffle.

Adarkar Wastes

{T}: Add {C}.
{T}: Add {W} or {U}. Adarkar Wastes deals 1 damage to you.

Order of the Alabaster Host

Whenever Order of the Alabaster Host becomes blocked by a creature, that creature gets -1/-1 until end of turn.

Order of the Mirror

{3}{W/P}: Transform Order of the Mirror. Activate only as a sorcery. ({W/P} can be paid with either {W} or 2 life.)

Order of the Mirror // Order of the Alabaster Host

Seachrome Coast

Seachrome Coast enters tapped unless you control two or fewer other lands.
{T}: Add {W} or {U}.

Preening Champion

Flying
When Preening Champion enters, create a 1/1 blue and red Elemental creature token.

Marshal of Zhalfir

Other Knights you control get +1/+1.
{W}{U}, {T}: Tap another target creature.

Teferi Akosa of Zhalfir

+1: Draw two cards. Then discard two cards unless you discard a creature card.
−2: You get an emblem with "Knights you control get +1/+0 and have ward {1}."
−3: Tap any number of untapped creatures you control. When you do, shuffle target nonland permanent an opponent controls with mana value X or less into its owner's library, where X is the number of creatures tapped this way.

Invasion of New Phyrexia

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When Invasion of New Phyrexia enters, create X 2/2 white and blue Knight creature tokens with vigilance.