A Ring of Mind Shielding has the following effect:
While wearing this ring, you are immune to magic that allows other creatures to read your thoughts, determine whether you are lying, know your Alignment, or know your creature type.
Jeremy Crawford has unofficially stated on Twitter that this ring does not protect against or have any interaction with the Zone of Truth spell.
Assuming that ruling to be true, what is the complete list of spells or other magic which the "determine whether you are lying" clause of the ring would provide immunity to?
My motivation behind this question is to discover if there even exists any such magic, or whether this clause of the Ring's text is effectively superfluous.
Best Answer
There are none
After a search on D&D Beyond for the term lying in any of the official rules, and one for truth there are no game elements that detect whether someone is lying in a magical way. There a number of monsters that "know if they hear a lie", but nothing hints that the traits are magical in nature.
The language is likely present in case a future game element allows the determination of lies without fully detecting thoughts (like the detect thoughts spell which is blocked by the first clause of the magic item). In the case of a future release of this sort, the clause would be pertinent.