Boreas Charger

Flying
When Boreas Charger leaves the battlefield, choose an opponent who controls more lands than you. Search your library for a number of Plains cards equal to the difference, reveal those cards, put one of them onto the battlefield tapped and the rest into your hand, then shuffle.

Deep Gnome Terramancer

Flash
Mold Earth — Whenever one or more lands enter the battlefield under an opponent's control without being played, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle. Do this only once each turn.

Loyal Warhound

Vigilance
When Loyal Warhound enters the battlefield, if an opponent controls more lands than you, search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.

Ramosian Rally

If you control a Plains, you may tap an untapped creature you control rather than pay this spell's mana cost.
Creatures you control get +1/+1 until end of turn.

Force of Virtue

If it's not your turn, you may exile a white card from your hand rather than pay this spell's mana cost.
Flash
Creatures you control get +1/+1.

Aerial Surveyor

Flying
Whenever Aerial Surveyor attacks, if defending player controls more lands than you, search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.
Crew 2

Reverent Mantra

You may exile a white card from your hand rather than pay this spell's mana cost.
Choose a color. All creatures gain protection from the chosen color until end of turn.

Abolish

You may discard a Plains card rather than pay this spell's mana cost.
Destroy target artifact or enchantment.

Claim Jumper

Vigilance
When Claim Jumper enters the battlefield, if an opponent controls more lands than you, you may search your library for a Plains card and put it onto the battlefield tapped. Then if an opponent controls more lands than you, repeat this process once. If you search your library this way, shuffle.

Angelic Favor

If you control a Plains, you may tap an untapped creature you control rather than pay this spell's mana cost.
Cast this spell only during combat.
Create a 4/4 white Angel creature token with flying. Exile it at the beginning of the next end step.

Knight of the White Orchid

First strike
When Knight of the White Orchid enters the battlefield, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield, then shuffle.

Keeper of the Accord

At the beginning of each opponent's end step, if that player controls more creatures than you, create a 1/1 white Soldier creature token.
At the beginning of each opponent's end step, if that player controls more lands than you, you may search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.

Shining Shoal

You may exile a white card with mana value X from your hand rather than pay this spell's mana cost.
The next X damage that a source of your choice would deal to you and/or creatures you control this turn is dealt to any target instead.

Loran of the Third Path

Vigilance
When Loran of the Third Path enters the battlefield, destroy up to one target artifact or enchantment.
{T}: You and target opponent each draw a card.

Space Marine Scout

First strike, vigilance
Concealed Position — When Space Marine Scout enters the battlefield, if an opponent controls more lands than you, you may search your library for a Plains card, put it onto the battlefield tapped, then shuffle.

Scouting Hawk

Flying
Keen Sight — When Scouting Hawk enters the battlefield, if an opponent controls more lands than you, search your library for a basic Plains card, put it onto the battlefield tapped, then shuffle.