Flesh Allergy

As an additional cost to cast this spell, sacrifice a creature.
Destroy target creature. Its controller loses life equal to the number of creatures that died this turn.

Fume Spitter

Sacrifice this creature: Put a -1/-1 counter on target creature.

Geth, Lord of the Vault

Intimidate (This creature can't be blocked except by artifact creatures and/or creatures that share a color with it.)
{X}{B}: Put target artifact or creature card with mana value X from an opponent's graveyard onto the battlefield under your control tapped. Then that player mills X cards.

Grasp of Darkness

Target creature gets -4/-4 until end of turn.

Poison Counter

Hand of the Praetors

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Other creatures you control with infect get +1/+1.
Whenever you cast a creature spell with infect, target player gets a poison counter.

Ichor Rats

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
When this creature enters, each player gets a poison counter.

Instill Infection

Put a -1/-1 counter on target creature.
Draw a card.

Memoricide

Choose a nonland card name. Search target player's graveyard, hand, and library for any number of cards with that name and exile them. Then that player shuffles.

Fulgent Distraction

Choose two target creatures. Tap those creatures, then unattach all Equipment from them.

Moriok Reaver

Necrogen Scudder

Flying
When this creature enters, you lose 3 life.

Necrotic Ooze

As long as this creature is on the battlefield, it has all activated abilities of all creature cards in all graveyards.

Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Painsmith

Whenever you cast an artifact spell, you may have target creature get +2/+0 and gain deathtouch until end of turn.

Plague Stinger

Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

Psychic Miasma

Target player discards a card. If a land card is discarded this way, return Psychic Miasma to its owner's hand.

Scars of Mirrodin