Thu 15 Feb 2024, 11:02
First, keep in mind that Elven Skill gives magical success equal to Proficiency Bonus and it resets after "a long rest" (not exactly after a day).
Usually, in every game i've played (including, for example Call of Cthulhu, Forbidden Lands, etc.), we try to limit the insight skill to sentences like: "he might be suspicious" or "he might hide something" and not telling openly if the NPC is lying and the specific information about he is lying. The opposite, that is telling exactly in which sense an NPC is lying, can easily derail the adventure every time players meet a hidden villain.
Another option, and maybe I am wrong understanding the rule, it's applying a contest between the elf player and NPC. The player would have a magical success but there could be a possibility for an NPC to roll for Charisma (Deception) so he could tie the contest.