Stoneshaker Shaman

At the beginning of each player's end step, that player sacrifices an untapped land of their choice.

Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Tremble

Each player sacrifices a land of their choice.

Mountain

Harsh Mentor

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

Manabarbs

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

Pillage

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

Darksteel Citadel

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.

Ankh of Mishra

Whenever a land enters, this artifact deals 2 damage to that land's controller.

Dingus Egg

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

Zo-Zu the Punisher

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

Valakut, the Molten Pinnacle

This land enters tapped.
Whenever a Mountain you control enters, if you control at least five other Mountains, you may have this land deal 3 damage to any target.
{T}: Add {R}.

Keldon Firebombers

When this creature enters, each player sacrifices all lands they control except for three.

Cemetery Gatekeeper

First strike
When this creature enters, exile a card from a graveyard.
Whenever a player plays a land or casts a spell, if it shares a card type with the exiled card, this creature deals 2 damage to that player.

Akki Blizzard-Herder

When this creature dies, each player sacrifices a land of their choice.

Ruination

Sulfuric Vortex

At the beginning of each player's upkeep, this enchantment deals 2 damage to that player.
If a player would gain life, that player gains no life instead.