Rowan's Battleguard

First strike
As long as you control a Rowan planeswalker, Rowan's Battleguard gets +3/+0.

Plains

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.

Idyllic Grange

({T}: Add {W}.)
Idyllic Grange enters tapped unless you control three or more other Plains.
When Idyllic Grange enters untapped, put a +1/+1 counter on target creature you control.

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.)

Youthful Knight

Wind-Scarred Crag

Wind-Scarred Crag enters tapped.
When Wind-Scarred Crag enters, you gain 1 life.
{T}: Add {R} or {W}.

Mountain

Venerable Knight

When Venerable Knight dies, put a +1/+1 counter on target Knight you control.

Prized Griffin

Rowan's Stalwarts

When Rowan's Stalwarts enters, you may search your library and/or graveyard for a card named Rowan, Fearless Sparkmage, reveal it, and put it into your hand. If you search your library this way, shuffle.

Rowan, Fearless Sparkmage

+1: Up to one target creature gets +3/+0 and gains first strike until end of turn.
−2: Rowan, Fearless Sparkmage deals 1 damage to each of up to two target creatures. Those creatures can't block this turn.
−9: Gain control of all creatures until end of turn. Untap them. They gain haste until end of turn.

Garrison Griffin

Flying
Whenever Garrison Griffin attacks, target Knight you control gains flying until end of turn.

Scorching Dragonfire

Scorching Dragonfire deals 3 damage to target creature or planeswalker. If that creature or planeswalker would die this turn, exile it instead.

Boulder Rush

Target creature gets +2/+0 until end of turn. (Then exile this card. You may cast the creature later from exile.)

Rimrock Knight

Rimrock Knight // Boulder Rush

Weaselback Redcap

{1}{R}: Weaselback Redcap gets +2/+0 until end of turn.

Chop Down

Destroy target creature with power 4 or greater. (Then exile this card. You may cast the creature later from exile.)

Giant Killer

Giant Killer // Chop Down

Dizzying Swoop

Tap up to two target creatures. (Then exile this card. You may cast the creature later from exile.)

Ardenvale Tactician

Ardenvale Tactician // Dizzying Swoop

Inspiring Veteran

Knight of the Keep

Weapon Rack

Weapon Rack enters with three +1/+1 counters on it.
{T}: Move a +1/+1 counter from Weapon Rack onto target creature. Activate only as a sorcery.