Marshal of Zhalfir

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

Surge of Salvation

You and permanents you control gain hexproof until end of turn. Prevent all damage that black and/or red sources would deal to creatures you control this turn.

Realmbreaker's Grasp

Enchant artifact or creature
Enchanted permanent can't attack or block, and its activated abilities can't be activated unless they're mana abilities.

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.

Island

Negate

Protocol Knight

When Protocol Knight enters, tap target creature an opponent controls. Put a stun counter on that creature if you control another Knight. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Zhalfirin Lancer

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

Elspeth's Smite

Elspeth's Smite deals 3 damage to target attacking or blocking creature. If that creature would die this turn, exile it instead.

Thunderhead Squadron

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying

Tranquil Cove

Tranquil Cove enters tapped.
When Tranquil Cove enters, you gain 1 life.
{T}: Add {W} or {U}.

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.

Invasion of New Phyrexia // Teferi Akosa of Zhalfir

Plains

Sigiled Sentinel

Backup 1 (When this creature enters, put a +1/+1 counter on target creature. If that's another creature, it gains the following ability until end of turn.)
Vigilance

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.

Change the Equation

Choose one —
• Counter target spell with mana value 2 or less.
• Counter target red or green spell with mana value 6 or less.