Gloom (11)
: Put the top card of your library into your graveyard.
Delirium — At the beginning of your end step, if there are four or more card types among cards in your graveyard, transform Autumnal Gloom.
Douse in Gloom deals 2 damage to target creature and you gain 2 life.
Nonblack creatures get -1/-1 until end of turn.
White spells cost more to cast.
Activated abilities of white enchantments cost more to activate.
If combat damage would be dealt to Gloom Surgeon, prevent that damage and exile that many cards from the top of your library.
Flying
Threshold — As long as seven or more cards are in your graveyard, Gloomdrifter has "When Gloomdrifter enters the battlefield, nonblack creatures get -2/-2 until end of turn."
Destroy target creature. If that creature was green or white, its controller discards a card.
Reach
Gloomwidow can block only creatures with flying.
Destroy target creature with flying. If that creature was blue or black, create a 1/2 green Spider creature token with reach. (It can block creatures with flying.)
Reach (This creature can block creatures with flying.)
Wither (This deals damage to creatures in the form of -1/-1 counters.)
: Put the top card of your library into your graveyard.