Grim Monolith

Grim Monolith doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{4}: Untap Grim Monolith.

Mana Geyser

Add {R} for each tapped land your opponents control.

Swamp

Pyretic Ritual

Jeweled Lotus

{T}, Sacrifice Jeweled Lotus: Add three mana of any one color. Spend this mana only to cast your commander.

Badlands

Fellwar Stone

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

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

Vial Smasher the Fierce

Whenever you cast your first spell each turn, choose an opponent at random. Vial Smasher the Fierce deals damage equal to that spell's mana value to that player or a planeswalker that player controls.
Partner (You can have two commanders if both have partner.)

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Blood Crypt

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

Ancient Tomb

{T}: Add {C}{C}. Ancient Tomb deals 2 damage to you.

Sol Ring

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. Talisman of Indulgence deals 1 damage to you.

Mox Diamond

If Mox Diamond would enter, you may discard a land card instead. If you do, put Mox Diamond onto the battlefield. If you don't, put it into its owner's graveyard.
{T}: Add one mana of any color.

Mana Crypt

At the beginning of your upkeep, flip a coin. If you lose the flip, Mana Crypt deals 3 damage to you.
{T}: Add {C}{C}.

Dragonskull Summit

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

Sign in Blood

Target player draws two cards and loses 2 life.

Luxury Suite

Luxury Suite enters tapped unless you have two or more opponents.
{T}: Add {B} or {R}.

Seething Song

Rakdos Signet

Mana Vault

Mana Vault doesn't untap during your untap step.
At the beginning of your upkeep, you may pay {4}. If you do, untap Mana Vault.
At the beginning of your draw step, if Mana Vault is tapped, it deals 1 damage to you.
{T}: Add {C}{C}{C}.

Arcane Signet

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

Dark Ritual

Command Tower

Graven Cairns

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

Cabal Coffers

{2}, {T}: Add {B} for each Swamp you control.

Neheb, the Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
At the beginning of each of your postcombat main phases, add {R} for each 1 life your opponents have lost this turn.

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Thought Vessel

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

Mountain

Divergent Transformations

Undaunted (This spell costs {1} less to cast for each opponent.)
Exile two target creatures. For each of those creatures, its controller reveals cards from the top of their library until they reveal a creature card, puts that card onto the battlefield, then shuffles the rest into their library.

Foreboding Ruins

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

Chrome Mox

Imprint — When Chrome Mox enters, you may exile a nonartifact, nonland card from your hand.
{T}: Add one mana of any of the exiled card's colors.

Reflecting Pool

{T}: Add one mana of any type that a land you control could produce.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Krark, the Thumbless

Whenever you cast an instant or sorcery spell, flip a coin. If you lose the flip, return that spell to its owner's hand. If you win the flip, copy that spell, and you may choose new targets for the copy.
Partner (You can have two commanders if both have partner.)

Exotic Orchard

Tainted Peak

{T}: Add {C}.
{T}: Add {B} or {R}. Activate only if you control a Swamp.

Syphon Mind

Each other player discards a card. You draw a card for each card discarded this way.

Night's Whisper

Bloodstained Mire

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

Shadowblood Ridge

Crypt Ghast

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever you tap a Swamp for mana, add an additional {B}.