Bend or Break

Each player separates all nontoken lands they control into two piles. For each player, one of their piles is chosen by one of their opponents of their choice. Destroy all lands in the chosen piles. Tap all lands in the other piles.

Ruination

Llanowar Elves

Wake of Destruction

Destroy target land and all other lands with the same name as that land.

Decree of Annihilation

Exile all artifacts, creatures, and lands from the battlefield, all cards from all graveyards, and all cards from all hands.
Cycling {5}{R}{R} ({5}{R}{R}, Discard this card: Draw a card.)
When you cycle this card, destroy all lands.

Jokulhaups

Destroy all artifacts, creatures, and lands. They can't be regenerated.

Devastation

Birds of Paradise

Nissa, Resurgent Animist

Landfall — Whenever a land you control enters, add one mana of any color. Then if this is the second time this ability has resolved this turn, reveal cards from the top of your library until you reveal an Elf or Elemental card. Put that card into your hand and the rest on the bottom of your library in a random order.

Orcish Settlers

{X}{X}{R}, {T}, Sacrifice this creature: Destroy X target lands.

Ramunap Excavator

Ib Halfheart, Goblin Tactician

Whenever another Goblin you control becomes blocked, sacrifice it. If you do, it deals 4 damage to each creature blocking it.
Sacrifice two Mountains: Create two 1/1 red Goblin creature tokens.

Fyndhorn Elves

From the Ashes

Destroy all nonbasic lands. For each land destroyed this way, its controller may search their library for a basic land card and put it onto the battlefield. Then each player who searched their library this way shuffles.

Obliterate

This spell can't be countered.
Destroy all artifacts, creatures, and lands. They can't be regenerated.

Popular Entertainer

Commander creatures you own have "Whenever one or more creatures you control deal combat damage to a player, goad target creature that player controls." (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)

Wildfire

Each player sacrifices four lands of their choice. Wildfire deals 4 damage to each creature.

Impending Disaster

At the beginning of your upkeep, if there are seven or more lands on the battlefield, sacrifice this enchantment and destroy all lands.

Erinis, Gloom Stalker

Deathtouch
Whenever Erinis attacks, return target land card from your graveyard to the battlefield.
Choose a Background (You can have a Background as a second commander.)

Anarchy

Mine Layer

{1}{R}, {T}: Put a mine counter on target land.
Whenever a land with a mine counter on it becomes tapped, destroy it.
When this creature leaves the battlefield, remove all mine counters from all lands.