Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Brave the Elements

Choose a color. White creatures you control gain protection from the chosen color until end of turn.

Arcane Signet

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

Teysa, Orzhov Scion

Sacrifice three white creatures: Exile target creature.
Whenever another black creature you control dies, create a 1/1 white Spirit creature token with flying.

Savai Triome

({T}: Add {R}, {W}, or {B}.)
Savai Triome enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Crackdown

Nonwhite creatures with power 3 or greater don't untap during their controllers' untap steps.

Crusade

Oros, the Avenger

Flying
Whenever Oros, the Avenger deals combat damage to a player, you may pay {2}{W}. If you do, Oros deals 3 damage to each nonwhite creature.

Resplendent Mentor

White creatures you control have "{T}: You gain 1 life."

Command Tower

Crovax, Ascendant Hero

Other white creatures get +1/+1.
Nonwhite creatures get -1/-1.
Pay 2 life: Return Crovax, Ascendant Hero to its owner's hand.

Divine Sacrament

White creatures get +1/+1.
Threshold — White creatures get an additional +1/+1 as long as seven or more cards are in your graveyard.

Honor of the Pure

Paragon of New Dawns

Other white creatures you control get +1/+1.
{W}, {T}: Another target white creature you control gains vigilance until end of turn. (Attacking doesn't cause it to tap.)

Righteous War

White creatures you control have protection from black.
Black creatures you control have protection from white.

Celestial Crusader

Flash
Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Flying
Other white creatures get +1/+1.