Smallpox

Each player loses 1 life, discards a card, sacrifices a creature of their choice, then sacrifices a land of their choice.

Break the Ice

Destroy target land that is snow or could produce {C}.
Overload {4}{B}{B} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Vampiric Link

Enchant creature
Whenever enchanted creature deals damage, you gain that much life.

Inquisition of Kozilek

Target player reveals their hand. You choose a nonland card from it with mana value 3 or less. That player discards that card.

Dreadhorde Invasion

At the beginning of your upkeep, you lose 1 life and amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)
Whenever a Zombie token you control with power 6 or greater attacks, it gains lifelink until end of turn.

Pooling Venom

Enchant land
Whenever enchanted land becomes tapped, its controller loses 2 life.
{3}{B}: Destroy enchanted land.

Defile

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

Contaminated Bond

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Whenever enchanted creature attacks or blocks, its controller loses 3 life.

Befoul

Destroy target land or nonblack creature. It can't be regenerated.

Sign in Blood

Target player draws two cards and loses 2 life.

Contaminated Ground

Enchant land
Enchanted land is a Swamp.
Whenever enchanted land becomes tapped, its controller loses 2 life.

Swamp

Sinister Possession

Enchant creature
Whenever enchanted creature attacks or blocks, its controller loses 2 life.

Lithoform Blight

Enchant land
When Lithoform Blight enters, draw a card.
Enchanted land loses all land types and abilities and has "{T}: Add {C}" and "{T}, Pay 1 life: Add one mana of any color."

Corrupted Roots

Enchant Forest or Plains
Whenever enchanted land becomes tapped, its controller loses 2 life.