Feats

Boon of the Soul Drinker

Prerequisite
Level 19+
Ability Score Increase
+1 to any ability score (max 30)
Source
FRHoF

You gain the following benefits.

Grave Resistance

You have Resistance to Cold damage and Necrotic damage.

Siphon Life

When an enemy within 120 feet of you is reduced to 0 Hit Points, you can take a Reaction to regain 50 Hit Points. Once you use this benefit, you can't use it again until you finish a Short or Long Rest.