Plains

Lay Down Arms

Exile target creature with mana value less than or equal to the number of Plains you control. Its controller gains 3 life.

Aeronaut Cavalry

Flying
When Aeronaut Cavalry enters, put a +1/+1 counter on another target Soldier you control.

Warlord's Elite

As an additional cost to cast this spell, tap two untapped artifacts, creatures, and/or lands you control.

Static Net

When Static Net enters, exile target nonland permanent an opponent controls until Static Net leaves the battlefield.
When Static Net enters, you gain 2 life and create a tapped Powerstone token. (It's an artifact with "{T}: Add {C}. This mana can't be spent to cast a nonartifact spell.")

Ambush Paratrooper

Flash
Flying
{5}: Creatures you control get +1/+1 until end of turn.

Phalanx Vanguard

Vigilance
Whenever an artifact you control enters, Phalanx Vanguard gets +1/+0 until end of turn.

Thopter Architect

Whenever an artifact you control enters, target creature gains flying until end of turn.

Rescue Retriever

Flash
When Rescue Retriever enters, put a +1/+1 counter on each other Soldier you control.
Prevent all damage that would be dealt to other attacking Soldiers you control.

Veteran's Powerblade

Equipped creature gets +2/+0.
Equip Soldier {W}
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Yotian Frontliner

Whenever Yotian Frontliner attacks, another target creature you control gets +1/+1 until end of turn.
Unearth {W} ({W}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Scrapwork Cohort

When Scrapwork Cohort enters, create a 1/1 colorless Soldier artifact creature token.
Unearth {2}{W} ({2}{W}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)