Ghost Quarter

{T}: Add {C}.
{T}, Sacrifice Ghost Quarter: Destroy target land. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.

Koth, Fire of Resistance

+2: Search your library for a basic Mountain card, reveal it, put it into your hand, then shuffle.
−3: Koth, Fire of Resistance deals damage to target creature equal to the number of Mountains you control.
−7: You get an emblem with "Whenever a Mountain you control enters, this emblem deals 4 damage to any target."

Darksteel Citadel

Slagwoods Bridge

Slagwoods Bridge enters tapped.
Indestructible
{T}: Add {R} or {G}.

The Elder Dragon War

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — The Elder Dragon War deals 2 damage to each creature and each opponent.
II — Discard any number of cards, then draw that many cards.
III — Create a 4/4 red Dragon creature token with flying.

Chandra, Torch of Defiance

+1: Exile the top card of your library. You may cast that card. If you don't, Chandra, Torch of Defiance deals 2 damage to each opponent.
+1: Add {R}{R}.
−3: Chandra, Torch of Defiance deals 4 damage to target creature.
−7: You get an emblem with "Whenever you cast a spell, this emblem deals 5 damage to any target."

Pillage

Destroy target artifact or land. It can't be regenerated.

Mountain

Burning of Xinye

You destroy four lands you control, then target opponent destroys four lands they control. Then Burning of Xinye deals 4 damage to each creature.

Flame Slash

Flame Slash deals 4 damage to target creature.

Geomancer's Gambit

Destroy target land. Its controller may search their library for a basic land card, put it onto the battlefield, then shuffle.
Draw a card.

Countryside Crusher

At the beginning of your upkeep, reveal the top card of your library. If it's a land card, put it into your graveyard and repeat this process.
Whenever a land card is put into your graveyard from anywhere, put a +1/+1 counter on Countryside Crusher.

Gut, True Soul Zealot

Whenever you attack, you may sacrifice another creature or an artifact. If you do, create a 4/1 black Skeleton creature token with menace that's tapped and attacking. (It can't be blocked except by two or more creatures.)
Choose a Background (You can have a Background as a second commander.)

Chandra, Acolyte of Flame

0: Put a loyalty counter on each red planeswalker you control.
0: Create two 1/1 red Elemental creature tokens. They gain haste. Sacrifice them at the beginning of the next end step.
−2: You may cast target instant or sorcery card with mana value 3 or less from your graveyard. If that spell would be put into your graveyard, exile it instead.

Cleansing Wildfire

Destroy target land. Its controller may search their library for a basic land card, put it onto the battlefield tapped, then shuffle.
Draw a card.

Bust

Boom

Destroy target land you control and target land you don't control.

Boom // Bust

Stomp

Damage can't be prevented this turn. Stomp deals 2 damage to any target.

Bonecrusher Giant

Whenever Bonecrusher Giant becomes the target of a spell, Bonecrusher Giant deals 2 damage to that spell's controller.