ok, this link.
quoting the feats wording: A number of times per day equal to your Wisdom bonus, you can feast upon the life essence of a creature that you hit with a scythe.
does this mean or is this a RAW/ RAI interpretation. That an undead who has no life essence. Cannot be the target of this attack, or is it being generalistic and saying anything you hit can be affected.
I'm dming a tyrant's grasp game and this seems like it should not affect Constructs or Undead as they aren't alive. I would think creatures with a con score have a life essence.
In times when i can't reason out the answer i generally go with the majority consensus of the forums unless i feel adamant about something.
What follows is the rules part of the ability:
« Activating this ability is a swift action.
When you do so, you gain a number of temporary hit points equal to the damage you dealt with the scythe attack. These temporary hit points last for 1 minute and don’t stack. »
While I understand why you could think it is applicable only against living beings, no such thing is mentioned in the rules text. Also, I can easily envision a corruption of the body of a construct or of an undead, which would work with explaining why these aren't immune to the hunger of the Pallid Princess.