Nausea

All creatures get -1/-1 until end of turn.

Nekrataal

First strike
When this creature enters, destroy target nonartifact, nonblack creature. That creature can't be regenerated.

Crossbow Infantry

{T}: This creature deals 1 damage to target attacking or blocking creature.

Nightmare

Flying (This creature can't be blocked except by creatures with flying or reach.)
Nightmare's power and toughness are each equal to the number of Swamps you control.

Persecute

Choose a color. Target player reveals their hand and discards all cards of that color.

Phyrexian Arena

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

Phyrexian Plaguelord

{T}, Sacrifice this creature: Target creature gets -4/-4 until end of turn.
Sacrifice a creature: Target creature gets -1/-1 until end of turn.

Plague Beetle

Swampwalk (This creature can't be blocked as long as defending player controls a Swamp.)

Plague Wind

Destroy all creatures you don't control. They can't be regenerated.

Eighth Edition