Mayhem Devil

Whenever a player sacrifices a permanent, this creature deals 1 damage to any target.

Exotic Orchard

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

Harnfel, Horn of Bounty

Discard a card: Exile the top two cards of your library. You may play those cards this turn.

Birgi, God of Storytelling

Whenever you cast a spell, add {R}. Until end of turn, you don't lose this mana as steps and phases end.
Creatures you control can boast twice during each of your turns rather than once.

Birgi, God of Storytelling // Harnfel, Horn of Bounty

Marsh Flats

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

Great Furnace

Starting Town

This land enters tapped unless it's your first, second, or third turn of the game.
{T}: Add {C}.
{T}, Pay 1 life: Add one mana of any color.

Graven Cairns

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

Command Tower

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

Arid Mesa

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

Vault of Whispers

Mountain

City of Brass

Whenever this land becomes tapped, it deals 1 damage to you.
{T}: Add one mana of any color.

Treasure Nabber

Whenever an opponent taps an artifact for mana, gain control of that artifact until the end of your next turn.

Shadow the Hedgehog

Haste
Whenever Shadow the Hedgehog or another creature you control with flash or haste dies, draw a card.
Chaos Control — Each spell you cast has split second if mana from an artifact was spent to cast it. (As long as it's on the stack, players can't cast spells or activate abilities that aren't mana abilities.)

Blazemire Verge

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

Luxury Suite

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

Mount Doom

{T}, Pay 1 life: Add {B} or {R}.
{1}{B}{R}, {T}: Mount Doom deals 1 damage to each opponent.
{5}{B}{R}, {T}, Sacrifice Mount Doom and a legendary artifact: Choose up to two creatures, then destroy the rest. Activate only as a sorcery.

Arena of Glory

This land enters tapped unless you control a Mountain.
{T}: Add {R}.
{R}, {T}, Exert this land: Add {R}{R}. If that mana is spent on a creature spell, it gains haste until end of turn. (An exerted permanent won't untap during your next untap step.)

Mana Confluence

{T}, Pay 1 life: Add one mana of any color.

Emergence Zone

{T}: Add {C}.
{1}, {T}, Sacrifice this land: You may cast spells this turn as though they had flash.

Storm-Kiln Artist

This creature gets +1/+0 for each artifact you control.
Magecraft — Whenever you cast or copy an instant or sorcery spell, create a Treasure token.

Polluted Delta

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

Swamp

Dragon's Rage Channeler

Whenever you cast a noncreature spell, surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)
Delirium — As long as there are four or more card types among cards in your graveyard, this creature gets +2/+2, has flying, and attacks each combat if able.

Dualcaster Mage

Flash
When this creature enters, copy target instant or sorcery spell. You may choose new targets for the copy.

Blood Crypt

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

Badlands

Forbidden Orchard

{T}: Add one mana of any color.
Whenever you tap this land for mana, target opponent creates a 1/1 colorless Spirit creature token.

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. This land deals 1 damage to you.

Ancient Tomb

{T}: Add {C}{C}. This land deals 2 damage to you.

Verdant Catacombs

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

Gemstone Caverns

If this card is in your opening hand and you're not the starting player, you may begin the game with Gemstone Caverns on the battlefield with a luck counter on it. If you do, exile a card from your hand.
{T}: Add {C}. If Gemstone Caverns has a luck counter on it, instead add one mana of any color.

Urza's Saga

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — This Saga gains "{T}: Add {C}."
II — This Saga gains "{2}, {T}: Create a 0/0 colorless Construct artifact creature token with 'This token gets +1/+1 for each artifact you control.'"
III — Search your library for an artifact card with mana cost {0} or {1}, put it onto the battlefield, then shuffle.

Bloodstained Mire

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