Plains

Sol Ring

Righteous Cause

Whenever a creature attacks, you gain 1 life.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Karlov of the Ghost Council

Whenever you gain life, put two +1/+1 counters on Karlov of the Ghost Council.
{W}{B}, Remove six +1/+1 counters from Karlov of the Ghost Council: Exile target creature.

Soul's Attendant

Whenever another creature enters, you may gain 1 life.

Soul Warden

Whenever another creature enters, you gain 1 life.

Auriok Champion

Protection from black and from red
Whenever another creature enters, you may gain 1 life.