Chime of Night

Enchant creature
When this Aura is put into a graveyard from the battlefield, destroy target nonblack creature.

Engine Rat

Deathtouch
{5}{B}: Each opponent loses 2 life.

Clawing Torment

Enchant artifact or creature
As long as enchanted permanent is a creature, it gets -1/-1 and can't block.
Enchanted permanent has "At the beginning of your upkeep, you lose 1 life."

Rancid Rats

Skulk (This creature can't be blocked by creatures with greater power.)
Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)

Cast into Darkness

Enchant creature
Enchanted creature gets -2/-0 and can't block.

Typhoid Rats

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

Oubliette

When this enchantment enters, target creature phases out until this enchantment leaves the battlefield. Tap that creature as it phases in this way. (Auras and Equipment phase out with it. While permanents are phased out, they're treated as though they don't exist.)

Gray Merchant of Asphodel

When this creature enters, each opponent loses X life, where X is your devotion to black. You gain life equal to the life lost this way. (Each {B} in the mana costs of permanents you control counts toward your devotion to black.)

Swamp

Defile

Target creature gets -1/-1 until end of turn for each Swamp you control.

Ruin Rat

Deathtouch
When this creature dies, exile target card from an opponent's graveyard.