Ancestral Katana

Whenever a Samurai or Warrior you control attacks alone, you may pay {1}. When you do, attach Ancestral Katana to it.
Equipped creature gets +2/+1.
Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

Cartouche of Solidarity

Enchant creature you control
When Cartouche of Solidarity enters, create a 1/1 white Warrior creature token with vigilance.
Enchanted creature gets +1/+1 and has first strike. (It deals combat damage before creatures without first strike.)

Akki Ronin

Whenever a Samurai or Warrior you control attacks alone, you may discard a card. If you do, draw a card.

Gift of Wrath

Enchant artifact or creature
As long as enchanted permanent is a creature, it gets +2/+2 and has menace. (It can't be blocked except by two or more creatures.)
When Gift of Wrath leaves the battlefield, create a 2/2 red Spirit creature token with menace.

Plains

Wind-Scarred Crag

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {R} or {W}.

Brute Force

Target creature gets +3/+3 until end of turn.

Hyena Umbra

Enchant creature
Enchanted creature gets +1/+1 and has first strike.
Umbra armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Oblivion Ring

When Oblivion Ring enters, exile another target nonland permanent.
When Oblivion Ring leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Peerless Samurai

Menace (This creature can't be blocked except by two or more creatures.)
Whenever a Samurai or Warrior you control attacks alone, the next spell you cast this turn costs {1} less to cast.

Battle-Mad Ronin

Bushido 2 (Whenever this creature blocks or becomes blocked, it gets +2/+2 until end of turn.)
Battle-Mad Ronin attacks each combat if able.

Devoted Retainer

Bushido 1 (Whenever this creature blocks or becomes blocked, it gets +1/+1 until end of turn.)

Mountain

Angelic Gift

Enchant creature
When Angelic Gift enters, draw a card.
Enchanted creature has flying.

Secluded Steppe

Secluded Steppe enters tapped.
{T}: Add {W}.
Cycling {W} ({W}, Discard this card: Draw a card.)

Eiganjo Exemplar

Whenever a Samurai or Warrior you control attacks alone, it gets +1/+1 until end of turn.

Call to Glory

Untap all creatures you control. Samurai creatures you control get +1/+1 until end of turn.

Magma Jet

Magma Jet deals 2 damage to any target. Scry 2.

Forgotten Cave

Forgotten Cave enters tapped.
{T}: Add {R}.
Cycling {R} ({R}, Discard this card: Draw a card.)

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Imperial Subduer

Whenever a Samurai or Warrior you control attacks alone, tap target creature you don't control.