Mace of the Valiant

Equipped creature gets +1/+1 for each charge counter on Mace of the Valiant and has vigilance.
Whenever a creature enters the battlefield under your control, put a charge counter on Mace of the Valiant.
Equip {3}

Alter Fate

Return target creature card from your graveyard to your hand. (Then exile this card. You may cast the creature later from exile.)

Order of Midnight

Order of Midnight // Alter Fate

Dauntless Bodyguard

As Dauntless Bodyguard enters the battlefield, choose another creature you control.
Sacrifice Dauntless Bodyguard: The chosen creature gains indestructible until end of turn.

Burning-Yard Trainer

Trample, haste
When Burning-Yard Trainer enters the battlefield, another target Knight you control gets +2/+2 and gains trample and haste until end of turn.

Steelclaw Lance

Equipped creature gets +2/+2.
Equip Knight {1}
Equip {3}

Sigiled Sword of Valeron

Equipped creature gets +2/+0, has vigilance, and is a Knight in addition to its other types.
Whenever equipped creature attacks, create a 2/2 white Knight creature token with vigilance that's attacking.
Equip {3}

Tournament Grounds

{T}: Add {C}.
{T}: Add {R}, {W}, or {B}. Spend this mana only to cast a Knight or Equipment spell.

Nomad Outpost

Nomad Outpost enters the battlefield tapped.
{T}: Add {R}, {W}, or {B}.

Plains

Knight of the Ebon Legion

{2}{B}: Knight of the Ebon Legion gets +3/+3 and gains deathtouch until end of turn.
At the beginning of your end step, if a player lost 4 or more life this turn, put a +1/+1 counter on Knight of the Ebon Legion. (Damage causes loss of life.)

Joust

Choose target creature you control and target creature you don't control. The creature you control gets +2/+1 until end of turn if it's a Knight. Then those creatures fight each other. (Each deals damage equal to its power to the other.)

Acclaimed Contender

When Acclaimed Contender enters the battlefield, 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.

Battle Display

Destroy target artifact. (Then exile this card. You may cast the creature later from exile.)

Embereth Shieldbreaker

Embereth Shieldbreaker // Battle Display

Swamp

Inspiring Veteran

Mountain

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Shining Armor

Flash
When Shining Armor enters the battlefield, attach it to target Knight you control.
Equipped creature gets +0/+2 and has vigilance.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)