Reflecting Pool

{T}: Add one mana of any type that a land you control could produce.

Arid Mesa

{T}, Pay 1 life, Sacrifice this land: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

This land enters tapped unless you have two or more opponents.
{T}: Add {R} or {W}.

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

{T}: Add {C}.
{R/W}, {T}: Add {R}{R}, {R}{W}, or {W}{W}.

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

({T}: Add {R} or {W}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.