Pact of the lich king

you may have died or just been down on your luck... but you did some how make a pact with the first lich. the lich king. whether it be by adorning the armor of his knights or by asking for life after death

lich lords Blessing

Starting at 1st level, when you reduce a hostile creature to 0 hit points, you may choose to raise it and give it one command

Dark One’s Own

Starting at 6th level, you can call on your patron for aid this can include but not limited to aid in battle, a skill check, instruction

 

lich kings favor

Starting at 10th level, you can choose one of the lich kings orders of death knight

order of the ice crown: when there are no allies in melee with you then you have double proficiency  on melee attacks

order of frostmourne:  when you kill another creature and raise them you may gain one of the creatures modifiers and add it to the appropriate score till you take a long rest

For The Lich King

Starting at 14th level, you gain control of a squad of greater, major, or 1 legendary undead 

greater 2d6 CR 7-13

major 1d4 CR 14-18

legendary 1 CR 18-20