Blackwillow Tree

Blackwillows are a type of spindly grey willow, with almost skeletal-like branches and a thick bough that produces a black, tar-like sap. Blackwillows are typically only found in areas that have been corrupted by the Shadowfell or areas with extreme necrotic influences. 
The Blackwillow produces a black, tar-like sap that draws theUndead to its location. If a creature that is Undead consumes this black sap, they become completely immune to fear and their senses are improved dramatically. Living creatures that consumes this black sap can become poisoned and weak to the point of being further prone to dangerous necrotic energy. The black sap can be distilled into a potent poison called the Blackwillow Poison.