Ruination

Barbflare Gremlin

First strike, haste
Whenever a player taps a land for mana, if Barbflare Gremlin is tapped, that player adds one mana of any type that land produced. Then that land deals 1 damage to that player.

Dingus Egg

Whenever a land is put into a graveyard from the battlefield, Dingus Egg deals 2 damage to that land's controller.

Manabarbs

Whenever a player taps a land for mana, Manabarbs deals 1 damage to that player.

Smokestack

At the beginning of your upkeep, you may put a soot counter on Smokestack.
At the beginning of each player's upkeep, that player sacrifices a permanent of their choice for each soot counter on Smokestack.

Jokulhaups

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

Ankh of Mishra

Whenever a land enters, Ankh of Mishra deals 2 damage to that land's controller.

Harsh Mentor

Whenever an opponent activates an ability of an artifact, creature, or land on the battlefield, if it isn't a mana ability, Harsh Mentor deals 2 damage to that player.

Zo-Zu the Punisher

Whenever a land enters, Zo-Zu the Punisher deals 2 damage to that land's controller.