Caltrops

Whenever a creature attacks, Caltrops deals 1 damage to it.

Tainted Aether

Whenever a creature enters, its controller sacrifices a creature or land of their choice.

Syphon Soul

Syphon Soul deals 2 damage to each other player. You gain life equal to the damage dealt this way.

Death Pits of Rath

Whenever a creature is dealt damage, destroy it. It can't be regenerated.

Soul Feast

Target player loses 4 life and you gain 4 life.

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. Sulfurous Springs deals 1 damage to you.

Power Surge

At the beginning of each player's upkeep, Power Surge deals X damage to that player, where X is the number of untapped lands they controlled at the beginning of this turn.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Dark Ritual

Lightning Bolt

Lightning Bolt deals 3 damage to any target.