Swamp

Island

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

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

({T}: Add {B} or {R}.)
Smoldering Marsh enters tapped unless you control two or more basic lands.

{T}: Add {C}.
{T}: Add {U} or {R}. Shivan Reef deals 1 damage to you.

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

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

{T}: Add {C}.
{T}: Add {B} or {R}. Sulfurous Springs deals 1 damage to you.

Menace
Whenever Obeka, Splitter of Seconds deals combat damage to a player, you get that many additional upkeep steps after this phase.