Sulfur Falls

This land enters tapped unless you control an Island or a Mountain.
{T}: Add {U} or {R}.

Rakdos Signet

Drowned Catacomb

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

Dimir Signet

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Talisman of Dominance

{T}: Add {C}.
{T}: Add {U} or {B}. This artifact deals 1 damage to you.

Arcane Signet

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

Xander's Lounge

({T}: Add {U}, {B}, or {R}.)
This land enters tapped.
Cycling {3} ({3}, Discard this card: Draw a card.)

Command Tower

Obeka, Splitter of Seconds

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

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Crumbling Necropolis

This land enters tapped.
{T}: Add {U}, {B}, or {R}.

Counterspell

Dragonskull Summit

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

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control. It can attack and {T} no matter when it came under your control.)
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)