Rancid Earth

Destroy target land.
Threshold — If seven or more cards are in your graveyard, instead destroy that land and Rancid Earth deals 1 damage to each creature and each player.

Geth's Verdict

Target player sacrifices a creature and loses 1 life.

Swamp

Peat Bog

Peat Bog enters tapped with two depletion counters on it.
{T}, Remove a depletion counter from Peat Bog: Add {B}{B}. If there are no depletion counters on Peat Bog, sacrifice it.

Choking Sands

Destroy target non-Swamp land. If that land was nonbasic, Choking Sands deals 2 damage to the land's controller.

Icequake

Destroy target land. If that land was a snow land, Icequake deals 1 damage to that land's controller.

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Dark Ritual

Thorn of the Black Rose

Deathtouch
When Thorn of the Black Rose enters, you become the monarch.

Chittering Rats

When Chittering Rats enters, target opponent puts a card from their hand on top of their library.

Witch's Cottage

({T}: Add {B}.)
Witch's Cottage enters tapped unless you control three or more other Swamps.
When Witch's Cottage enters untapped, you may put target creature card from your graveyard on top of your library.

Gurmag Angler

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)