Prior to becoming an adventurer, your path in life was defined by one dark moment, one fateful decision, or one tragedy. Now you feel a darkness threatening to consume you, and you fear there may be no hope of escape. Choose a harrowing event that haunts you, or roll one on the Harrowing Events table.

At level 1 you can cast "spare the dying" and take 2 points of damage to stabilize and bring back a character or player with 1 hp once per short rest

At level 3 you can cast " Life Transference" once per long rest. 

At level 10 you get one free cast of Vampiric touch. 

At level 15 you can regain 1d8 hit points as many times up to your con modifier per long rest. If you lost a limb and hold it to the spot it was removed and use this ability, you can re-attach it. 

However,  such boons come at a price.  All spells draining life can count in the below effects. 

At level 3 you will need one small sip of blood, human or animal, once per day or else you will suffer one level of exhaustion as your sleep is interrupted by nightmares. 

At level 5 you will need one small cup of blood, animal or human,  once per day or even after a long rest you will suffer exhaustion as the nightmares plaguing you keep you from resting, even if you would not require sleep. 

At level 10 the hunger increases and you need one goblet ( Or flask )  of humanoid blood or a sentient creature per day. If you do not, you suffer the above penalties but you also get disadvantage on all charisma checks as you go into an irritated withdrawal. 

At level 15 You begin to become light-sensitive, needing to protect your eyes from normal or bright lights or suffer disadvantage on attack and skill rolls requiring sight. You also take 1d6 radiant damage per hour you are outside.