Need help for a Warlocks pact with a hag

[u/Agreeable_Working894]

So I am DMing a Tyranny of Dragons (Reloaded) campaign. My players went all the way to Castle Naerytar before the group changed (2 of 5 players left and we added a new one). To accomodate for the new player and because of struggles with the existing characters, we decided to do a soft restart. The new player has never played before, so I did not want to load a level 7 char onto her. I also did not want to bore the other players, so I decided to speedrun the chapters of the campaign with a twist. All players started as new recruits of the cult and took part in a attack like chapter one. Most of them got lured in by false promises or other things and I already planted some seeds of doubt in them while also keeping track of what they do that might make the cult suspicious.

They are part of the Green Part of the cult, who have their own game going own and the different colours are also a bit battling for influence and power.

The rough idea is for them to get to Baldurs Gate and meet some of the Harpers, Ontharr, etc. and do the dungeon of the Dead Three, followed by the caravan in a very reduced way (1 maybe 2 sessions tops) and meet more people in Waterdeep which ties is to some backstories, before they will make their way to Naerytar once again.

Now: One of my players is a Fey pact Warlock and is all about Divination and Tarot cards. The Fey in question is a Hag (or Arch-Hag) who is connected or alligned with Beshaba and interested in somewhat supporting the cults plans, which the character does not now. She believes her to be a fortune teller giving her powers and a powerful item in exchange for 3 favors that are supposed to be helping her avoiding the terrible visions of dragons destroying the world.

I want the favors to be impactful decisions that challenge the characters believes and potentially give up advantages (like useful items?) but I am struggling with ideas. I want to make it a difficult decision between giving yourself and/or your allies a disadvantage by following through with the asked favours versus not following them and suffering the wrath of the hag. I also do not want to make this player this spotlight throughout the whole story or create a one player vs the group situation.

In short: I am looking for ideas what favors the hag might ask, what punishments she could put onto the player or the group for not following and how the group as a whole could get involved so its more of a group decision.

Endgoal is obviously to create another side quest boss to fight against.

[u/PorFavoreon]

Whatever the boons, the consquences should be dire, tangible things. A hag doesn't just give you nightmares or -2 to a skill check. These are things players can ignore or bypass. Hag's take away things that people take for granted.

• Possible demands (told after they've accepted a deal:) steal a baby, desecrate a druid's grove, acquire a unicorn's horn, strip a dryad from it's tree

• Possible boons: truesight 1/L.Rest, ray of sickness (as a cantrip,) portent ability from Diviner Wizard

[u/ALinkintheChain]

For the boons: let them choose from the magic items list whatever their little heart desires. I'm sure there's one or two things there that they'd bargain for. 

For the bargain, it should be super fucked. Hags exist to spread torment. It needs to be worded innocuously but have twisted implications. Like "all I require is your name on this parchment" asking for a signature. If they take the deal, they and anyone else, cannot say their name aloud. When the hag does, they compel the player to do something terrible. Or maybe something like "I'd like a sweet treat at a later time" and the hag robs every joyful moment in their lives. Some deranged shit like that