The number of creatures you control is counted at the time the activated ability resolves
They can generate a lot of value over the course of a game if they're not dealt with, and even when taken out swiftly, force your opponent to divert their attention away from their main goal: killing you
Rarity is a key component in determining a Magic cards value, with rares and mythics typically demanding a higher price than commons and uncommons
She supplies a drain for every creature you play for the rest of the game, and she lets you recycle your Fenlurkers and Freebooters for additional cards (again useful in a mono-black deck)
Note that if you have 25 dorks in your deck, you should usually get 1 in your dig of four, so that's what I am aiming for
It seems likely that Many Partings and/or Shelob's Ambush will find a home in some sort of Asmoranomardicadaistinaculdacar shell