Typhoid Rats

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Screams from Within

Enchant creature
Enchanted creature gets -1/-1.
When enchanted creature dies, return Screams from Within from your graveyard to the battlefield.

Exquisite Blood

Whenever an opponent loses life, you gain that much life.

Grim Guardian

Constellation — Whenever Grim Guardian or another enchantment you control enters, each opponent loses 1 life.

Diabolic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Sanguine Bond

Whenever you gain life, target opponent loses that much life.

Swamp

Warehouse Tabby

Whenever an enchantment you control is put into a graveyard from the battlefield, create a 1/1 black Rat creature token with "This creature can't block."
{1}{B}: Warehouse Tabby gains deathtouch until end of turn.