The Rat Queen

Rats you control have deathtouch
{b}{b}, tap two untapped rat creature you own:
draw a card from your library
{b}{b}{b}{b}, sacrifice two rat creatures you own:
search your library for a card, reveal it, then
shuffle your library, put the card on top of your library.
They say there's strength in numbers, I agree, I'd also
say there's horror, cruelty, misery and death