Graven Cairns

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

Sulfurous Mire

({T}: Add {B} or {R}.)
This land enters tapped.

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

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

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

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