Watery Grave

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

Bojuka Bog

Bojuka Bog enters tapped.
When Bojuka Bog enters, exile target player's graveyard.
{T}: Add {B}.

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

Drowned Catacomb enters tapped unless you control an Island or a Swamp.
{T}: Add {U} or {B}.

({T}: Add {U} or {B}.)
Sunken Hollow enters tapped unless you control two or more basic lands.

Shipwreck Marsh enters tapped unless you control two or more other lands.
{T}: Add {U} or {B}.

{T}: Add {C}.
{T}: Add {U} or {B}. Underground River deals 1 damage to you.