The Circle of Loyalty

This spell costs {1} less to cast for each Knight you control.
Creatures you control get +1/+1.
Whenever you cast a legendary spell, create a 2/2 white Knight creature token with vigilance.
{3}{W}, {T}: Create a 2/2 white Knight creature token with vigilance.

Swordsworn Cavalier

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

Open the Armory

Search your library for an Aura or Equipment card, reveal it, put it into your hand, then shuffle.

Brave the Sands

Creatures you control have vigilance.
Each creature you control can block an additional creature each combat.

Codsworth, Handy Helper

Commanders you control have ward {2}.
{T}: Add {W}{W}. Spend this mana only to cast Aura and/or Equipment spells.
{T}: Attach target Aura or Equipment you control to target creature you control. Activate only as a sorcery.

Puresteel Paladin

Whenever an Equipment you control enters, you may draw a card.
Metalcraft — Equipment you control have equip {0} as long as you control three or more artifacts.

Fragmentize

Destroy target artifact or enchantment with mana value 4 or less.

Acclaimed Contender

When Acclaimed Contender enters, if you control another Knight, look at the top five cards of your library. You may reveal a Knight, Aura, Equipment, or legendary artifact card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Steelshaper's Gift

Search your library for an Equipment card, reveal that card, put it into your hand, then shuffle.

Danitha, Benalia's Hope

First strike, vigilance, lifelink
When Danitha, Benalia's Hope enters, you may put an Aura or Equipment card from your hand or graveyard onto the battlefield attached to Danitha.

Esper Sentinel

Whenever an opponent casts their first noncreature spell each turn, draw a card unless that player pays {X}, where X is Esper Sentinel's power.

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Chivalric Alliance

Whenever you attack with two or more creatures, draw a card.
{2}, Discard a card: Create a 2/2 white and blue Knight creature token with vigilance.

Always Watching

Nontoken creatures you control get +1/+1 and have vigilance.

Emeria, the Sky Ruin

Emeria, the Sky Ruin enters tapped.
At the beginning of your upkeep, if you control seven or more Plains, you may return target creature card from your graveyard to the battlefield.
{T}: Add {W}.

Dolmen Gate

Prevent all combat damage that would be dealt to attacking creatures you control.

Smothering Tithe

Whenever an opponent draws a card, that player may pay {2}. If the player doesn't, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Knight of Grace

First strike
Hexproof from black (This creature can't be the target of black spells or abilities your opponents control.)
Knight of Grace gets +1/+0 as long as any player controls a black permanent.

Sigarda's Aid

You may cast Aura and Equipment spells as though they had flash.
Whenever an Equipment you control enters, you may attach it to target creature you control.

Plains

Stonehewer Giant

Vigilance
{1}{W}, {T}: Search your library for an Equipment card, put it onto the battlefield, attach it to a creature you control, then shuffle.

Land Tax

At the beginning of your upkeep, if an opponent controls more lands than you, you may search your library for up to three basic land cards, reveal them, put them into your hand, then shuffle.