I'm going to throw out some YMTC ideas as I think of them, feedback appreciated!
Depraved Contract 1BB
Enchantment
As an additional cost to cast ~, sacrifice a White creature.
Put a 5/5 black Demon creature token with flying into play.
At the beginning of your upkeep, if you control no Demon creatures, Depraved Contract deals 5 damage to you.
Sacrifice 3 white creatures: Put a 5/5 black Demon creature token with flying into play.
(That may be too many lines of text)
Forcing white creatures could be a bit too restrictive, but I think the card is nice, and could work. Direct damage is a demon-y thing to do, but on an enchantment itself it sounds off, and could be changed to life loss. Here's my attempt:
Depraved Contract 1BB
Enchantment
At the beginning of your upkeep, if you control no Demon creatures, you lose 5 life.
Sacrifice three non-Demon creatures: Put a 5/5 black Demon creature token with flying onto the battlefield.
This way the card gives you some tension if you try to rush it out without enough creatures to power it, and would probably fit nicely word-wise. It could also use a new (unique) creature type to make sure it only doesn't hurt you if you summon some of its tokens; otherwise, it'd work fine as some sort of tribal enchantment. The non-demon clause could be removed if you want to make it fit for a demon tribal deck as well.
EDIT: Pasting previous double post
Though definitely secondarily to blue, mill is totally on color for black. It's true that it's never been a form of taxation before (to my knowledge), but that was kind of the point.
I also find it funny that your revision is still named Millow Fort even though it doesn't mill, ha. Your version is a lot closer to No Mercy.
Yeah, but I was thinking along the lines that it's too slow of an effect to be viable in constructed. There's no way milling a card per attack will let you mill them out unless they attack with 0/1s (20 counters = dead).
What if you'd get grudge counters equal to the combat damage dealt to you or your PWs, and you could use them either for milling or for building up a Haunting Echoes-like effect?
Da-yum at that hydra! I have fond memories of my Molten Hydra, and this seems like its ridiculously overpowered cousin, ready to take some names and turn limited games on their head, while still being an interesting constructed card. I'm definitely going to look for it, and I'm glad most of the card that are being spoiled are really interesting additions to the guild's card pools.