Hel

One of Loki’s three children with Angrboða (her siblings are the wolf Fenrir and Jörmungandr the world serpent), the gods knew from the start that Hel would be trouble. Odin himself threw her into Niflheim to “administer board and lodging to those sent to her, and that is those who die of sickness or old age.” So it is that she rules over the Norse afterlife other than Valhalla, in the Halls of Hel beneath one of the world tree Yggdrasil’s three roots. This realm is filled with great mansions that have high walls and enormous gates, and when Ragnarök comes Loki will arrive with the people kept here alongside him. Hel has a dish called Hunger, a knife called Famine, the servants Ganglati and Ganglöt, an entrance threshold called the "stumbling-block," the "sick-bed," and the curtains "gleaming-bale". Despite her divinity she is not a woman of great beauty however, possessing fierce features, often with a dejected demeanor, and a keen mind. When the god Baldr is brought to her halls she refuses to release him to his brother Hermóðr but offers to let him go if all things in the world will weep for him—yet the jötunn Þökk refuses to so she keeps him.

Hel is grim and fierce. She is merciless in destroying those who offend her.

Hel rarely conveys emotion, except for the occasional mocking smile.

She is neutral evil in alignment.

She is called "The Merciless". She is known as the Goddess of Death, or the Goddess of Death and the Underworld. Some know her as the Mistress of Death.

Helheim Attunement

Starting at 1st level, you are granted darkvision up to 60ft and cold resistance. Gain proficiency with magical armor and longswords.

After reaching level 10, you have spent enough time in Helheim and drawing on its power to gain Cold immunity, poison and necrotic resistance

Hel lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

Hel Expanded Spells

Spell Level	Spells
1st	guiding bolt, healing word,inflict wounds
2nd	blindness/deafness, spiritual weapon, aid, detect thoughts
3rd	animate dead, fear, revivify, spirit guardians
4th	confusion, phantasmal killer, divination
5th	raise dead , telekinesis, commune

Helheim Spellcaster

At level 6, You can now draw power directly from Helheim, you gain the spells Spirit Guardians and Vampiric Touch.

Gift of the Undead

Starting at 10th level, you can call on your patron as an action to summon 2 undead servants that obey your every command. When no command is given or previous command completed, the undead servants follow you and will defend you (if possible). Undead servants are standard creatures with their standard attack and defensive capabilities.

If you die while you have undead servants, they are immediately sent back to Helheim. Undead servants will stay if you die and use Hel's Blessing to prevent death. 

Undead servants do not need sleep or rest, and will stand watch while you rest. Once the undead servants die, Gift of the Undead cannot be used for 24 hours from when the creatures were summoned.

Once you reach Class level 10, you can summon CR 1,2,3 creatures. CR of creatures that can be summoned increases by 1 CR per 1 class level, up to a maximum of CR 13 at level 20 class level. 

Gift of the Undead can only be used once every 24 hours after a long rest. 

Hurl Through Helheim

Starting at 14th level, when you hit a target with an attack, you can use this feature to instantly rip open a realm tear. The target struck with the attack gets pulled through and hurtles through the frozen realm of the dead.

At the end of your next turn, the realm tear reopens and the target returns to the space it previously occupied, or the nearest unoccupied space. If the target is not an undead creature, it takes 5d10 cold damage and 5d10 psychic damage as it reels from the horrific frozen experience. Undead creature takes half damage.  

Once you use this feature, you can’t use it again until you finish a long rest.