undead and constructs are valid targets by RAW.
I mean, if you follow the logic, undead are “animated corpses” and constructs are “animated objects”, sooo… Sure, the “Rule of Cool” wins my vote on this.
Should have a fire trap that works on a timer, but also activates from a pressure plate. You think you’ve got it figured out, then fwoosh, incinerated.
If I roll out all the bad numbers first, I’ll only have good numbers when it counts!
Actuality: Every bullshit nonsense joke roll comes up 18-20, while every roll in the climatic finale combat scene is 1-4.
But you also should design feats so as not to punish players for trying to express their character concept a different way. Why not just make one feat to have a prehensile tail?