Ruination

Price of Glory

Whenever a player taps a land for mana, if it's not that player's turn, destroy that land.

Impending Disaster

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

Crucible of Worlds

Armageddon

Wildfire

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

Velomachus Lorehold

Flying, vigilance, haste
Whenever Velomachus Lorehold attacks, look at the top seven cards of your library. You may cast an instant or sorcery spell with mana value less than or equal to Velomachus Lorehold's power from among them without paying its mana cost. Put the rest on the bottom of your library in a random order.

Fall of the Thran

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Destroy all lands.
II, III — Each player returns two land cards from their graveyard to the battlefield.

Bust

Boom

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

Boom // Bust

Catastrophe

Destroy all lands or all creatures. Creatures destroyed this way can't be regenerated.