Underground Sea

Flooded Strand

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

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

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

Isolated Chapel enters tapped unless you control a Plains or a Swamp.
{T}: Add {W} or {B}.

({T}: Add {W} or {U}.)
Prairie Stream enters tapped unless you control two or more basic lands.

Shattered Sanctum enters tapped unless you control two or more other lands.
{T}: Add {W} or {B}.

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

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

Morphic Pool enters tapped unless you have two or more opponents.
{T}: Add {U} or {B}.

Sea of Clouds enters tapped unless you have two or more opponents.
{T}: Add {W} or {U}.

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

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

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

({T}: Add {W}, {U}, or {B}.)
Raffine's Tower enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

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

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Deserted Beach enters tapped unless you control two or more other lands.
{T}: Add {W} or {U}.

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Vault of Champions enters tapped unless you have two or more opponents.
{T}: Add {W} or {B}.