Sign in Blood

Target player draws two cards and loses 2 life.

Drainpipe Vermin

When Drainpipe Vermin dies, you may pay {B}. If you do, target player discards a card.

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Wight of Precinct Six gets +1/+1 for each creature card in your opponents' graveyards.

Target opponent reveals their hand. You choose a noncreature, nonland card from it. That player discards that card.

Pack Rat's power and toughness are each equal to the number of Rats you control.
{2}{B}, Discard a card: Create a token that's a copy of Pack Rat.

Whenever another nontoken creature dies, you may create a 1/1 black Rat creature token.
Rats you control have deathtouch.

Enchant creature
Enchanted creature gets -X/-X, where X is the number of creature cards in its controller's graveyard.

When Ravenous Rats enters, target opponent discards a card.

Target player sacrifices a creature of their choice, then gains life equal to that creature's toughness.