Arcane Signet

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

Command Tower

Exotic Orchard

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

Kenrith, the Returned King

{R}: All creatures gain trample and haste until end of turn.
{1}{G}: Put a +1/+1 counter on target creature.
{2}{W}: Target player gains 5 life.
{3}{U}: Target player draws a card.
{4}{B}: Put target creature card from a graveyard onto the battlefield under its owner's control.