Mountain

Truefire Captain

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Whenever Truefire Captain is dealt damage, it deals that much damage to target player.

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.

Garrison Griffin

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

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.)

Inspiring Veteran

Scorching Dragonfire

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

Fireborn Knight

Double strike
{R/W}{R/W}{R/W}{R/W}: Fireborn Knight gets +1/+1 until end of turn.

Plains

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

Venerable Knight

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

Jousting Dummy

{3}: Jousting Dummy gets +1/+0 until end of turn.

Wind-Scarred Crag

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