Aragorn, the Uniter

Whenever you cast a white spell, create a 1/1 white Human Soldier creature token.
Whenever you cast a blue spell, scry 2.
Whenever you cast a red spell, Aragorn, the Uniter deals 3 damage to target opponent.
Whenever you cast a green spell, target creature gets +4/+4 until end of turn.

Coastal Piracy

Whenever a creature you control deals combat damage to an opponent, you may draw a card.

Rolling Earthquake

Rolling Earthquake deals X damage to each creature without horsemanship and each player.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

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.

Wu Scout

Horsemanship (This creature can't be blocked except by creatures with horsemanship.)
When Wu Scout enters, look at target opponent's hand.

Allied Reinforcements

Create two 2/2 white Knight Ally creature tokens.

Reconnaissance Mission

Whenever a creature you control deals combat damage to a player, you may draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)

Edric, Spymaster of Trest

Whenever a creature deals combat damage to one of your opponents, its controller may draw a card.

Ink-Treader Nephilim

Whenever a player casts an instant or sorcery spell, if that spell targets only Ink-Treader Nephilim, copy the spell for each other creature that spell could target. Each copy targets a different one of those creatures.

Derevi, Empyrial Tactician

Flying
When Derevi, Empyrial Tactician enters and whenever a creature you control deals combat damage to a player, you may tap or untap target permanent.
{1}{G}{W}{U}: Put Derevi onto the battlefield from the command zone.

Enchant creature
Enchanted creature gets +2/+2, has first strike, and is a Knight in addition to its other types. (It deals combat damage before creatures without first strike.)

Inspiring Veteran

Banish into Fable

When you cast this spell from your hand, copy it if you control an artifact, then copy it if you control an enchantment. You may choose new targets for the copies.
Return target nonland permanent to its owner's hand. You create a 2/2 white Knight creature token with vigilance.

Azorius Knight-Arbiter

Vigilance
Azorius Knight-Arbiter can't be blocked.

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.

Yellow Scarves Cavalry

Horsemanship (This creature can't be blocked except by creatures with horsemanship.)
Yellow Scarves Cavalry can't block.

Riding the Dilu Horse

Target creature gets +2/+2 and gains horsemanship. (It can't be blocked except by creatures with horsemanship. This effect lasts indefinitely.)

Herald of Hoofbeats

Horsemanship (This creature can't be blocked except by creatures with horsemanship.)
Other Knights you control have horsemanship.

Merry-Go-Round

Visit — Creatures you control with power 2 or less gain horsemanship until end of turn. (They can't be blocked except by creatures with horsemanship.)

Sun Ce, Young Conquerer

Horsemanship (This creature can't be blocked except by creatures with horsemanship.)
When Sun Ce, Young Conquerer enters, you may return target creature to its owner's hand.

Balan, Wandering Knight

First strike
Balan, Wandering Knight has double strike as long as two or more Equipment are attached to it.
{1}{W}: Attach all Equipment you control to Balan.

Sun Quan, Lord of Wu

Creatures you control have horsemanship. (They can't be blocked except by creatures with horsemanship.)