This land enters tapped unless you control a Mountain. {T}: Add {R}. {R}, {T}, Exert this land: Add {R}{R}. If that mana is spent on a creature spell, it gains haste until end of turn. (An exerted permanent won't untap during your next untap step.)

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

{T}: Add {C}. {1}: This land becomes a 1/1 Blinkmoth artifact creature with flying until end of turn. It's still a land. {1}, {T}: Target Blinkmoth creature gets +1/+1 until end of turn.

This land enters tapped. When this land enters, return a land you control to its owner's hand. {T}: Add {R}{W}.

This land enters tapped unless you control a Mountain or a Plains. {T}: Add {R} or {W}.

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

{T}, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

As this land enters, you may reveal a Mountain or Plains card from your hand. If you don't, this land enters tapped. {T}: Add {R} or {W}.

({T}: Add {R}.)

This land enters tapped. {T}: Add {C}. {2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

({T}: Add {W}.)

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

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

This land enters tapped unless you control two or more other lands. {T}: Add {R} or {W}.