You have touched the Shadowfell and lived to speak of it. You even brought back a souvenir.

Senses DarkvisionSpeed , fly 6 (hover)Constant Benefits* You gain a +4 bonus to monster knowledge checks to identify undead creatures.
* You gain resist 5 necrotic. If already have resist necrotic, increase the resistance by 2.
Active BenefitsIncorporeal: The specter has phasing and does not provoke opportunity attacks.
Undead: The specter is immune to necrotic damage.

Published in Dragon Magazine 382, page(s) 29.