Innate Spellcasting.

The hag's innate spellcasting ability is intelligence(spell save DC 17, +7 to hit with spell attacks).

At will: detect magic, eldrich blast, hex

2/day: plane shift (self only), ray of enfeeblement, sleep, thunderstep,

Foreign telepathy

. The Shadowfell Hag cannot verbally communicate; a Shadowfell Hag can create a 2-way telepathic link between herself and any living creature she can see. This link breaks if the Shadowfell Hag cannot see the creature she is communicating with.

Magic Resistance

. The hag has advantage on saving throws against spells and other magical effects.

Ghastly Visage

. Any humanoid that starts its turn within 30 feet of the hag and can see the hag's true form must make a DC 15 Wisdom saving throw. On a failed save, the creature is paralysed for 1 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if the hag is within line of sight, ending the effect on itself on a success. Unless the target is surprised or the revelation of the hag's true form is sudden, the target can avert its eyes and avoid making the initial saving throw. Until the start of its next turn, a creature that averts its eyes has disadvantage on attack rolls against the hag. A Shadowfell Hag's apperance cannot be altered in such a way to hide their true nature; if a Shadowfell Hag alters or has its apperance altered, they still appear as a hag. When a humanoid views the Shadowfell Hag's altered appearance, they must make a DC 12 Wisdom saving throw. On a failed save, the creature is feared for 1 minute, and can repeat the save on their following turns to end the effect. On a successful saving throw, the humanoid is not feared. A creature that has been feared in this way cannot be feared again for the next 24 hours.  

CONTRACTS.

when a contract is made all players who agree to the contract are magically bound to the contract. the hag knows the following information about creatures who are bound by a contract:

there location at all times while on the material plane or in the Shadowfell

has a general idea of what the creature is doing at all times.

contract breaking (limited)

. these contracts are ones that are fairly mundane that are built more as a defence mechanism then a real contract. the hag chooses the method and how the creature agrees to the contract ie it could be walking in the door, taping a table three times, shaking there hand. the main rule is that limited contracts must be fulfilled withing 60ft of the hag, otherwise the contract is moderate or extreem. when this contract is broken the hag gains the ability to trigger shadow quake on all targets in the area.  

Shadow quake.

when a limited contract is broken, all players are pushed 30ft away from the hag, all players in a 30ft radius are knocked prone and make a wisdom saving throw. all players make a wisdom saving throw or believe a swarm of beetles are wrapped around them holding them to the ground. They are considered grappled and feared. all players who broke a contract auto fail this save    

Contract breaking (extream)

  the magical bond that is made when you sign a contract with a shadow hag should never be taken lightly. every day after the contract is broken additional stacking effects happen until the creature who breaks the contract goes to the shadowfell hag to deal with the situation.   1 day after contract is broken:

the hag is able to wisper into there mind

whenever the creature has a moment to themselves to reflect they cant help but hear skittering noises (of thousands of beetles)

on a long rest the DM rolls a 1d4, on a 2 or a 4 the creature cant sleep and doesnt benefit from a long rest. there dreams were full of beetles crawliing and chewing all over them

2 days after contract is broken

the shadowfell hag gains the ability to manipulate tiny creatures all around the creature. the hag starts to pull all creatures of size tiny withing a 20ft radius around the contract breaker towards them. these creatures will continue to follow the contract breaker around. to determine how many, every day roll a d20, that is how many more creatures follow

the shadowfell hag's wispers are becoming more madining, making the creature have disadvantage on wisdom saving throws.

whenever the creature rolls a 3 or lower on any d20 roll they loose there turn as they loose themselves to the sound of beetles crawling.

day 3:

the contract breakers eyes blacken as they constantly hear maddining wispers and the crawling of beetles. There intelligence score is reduced by 2 every day after this point.

every day after this point the contract breaker shrinks half a foot

the contract breaker also starts to slowly change into a creature that the hag would find useful. ie every day starting to grow feathers out of there skin (crow), there skin is hardening and blackening(beetle), there back is slowly growing wings (locust)

day 4:

on the d4 roll the player now looses there turn on a 2 or a 4

half movement

day 5:

the contract breaker no longer benefits from long or short rests

loose action

looses the ability to read or focus on anything for an extented period of time. as whenever they focus they see swarms of beetles (or other creatures) covering what they are focusing on (this means that for wizards they cant change there spells)

day 6:

the hag may choose at any time to dominate the contract breaker for 1 round/combat encounter. if you want to make it random roll d6 on a 6 you get dominated

day 7:

the contract breaker now has lost themselves and can only mutter a single phrase (up to dm)

day 8:

they bug (or other creature)