Toxic Deluge

As an additional cost to cast this spell, pay X life.
All creatures get -X/-X until end of turn.

Kaervek, the Spiteful

Dina, Soul Steeper

Whenever you gain life, each opponent loses 1 life.
{1}, Sacrifice another creature: Dina, Soul Steeper gets +X/+0 until end of turn, where X is the sacrificed creature's power.

Night of Souls' Betrayal

Polluted Bonds

Whenever a land an opponent controls enters, that player loses 2 life and you gain 2 life.

Nature's Revolt

All lands are 2/2 creatures that are still lands.