No review yet? This card rocks.

This is a very unique card. It is one of the few cards that will simply discard a location in play, without ever exploring it, with others being Bilbo's Plan, Distant Stars, and Eryn Galen Settler. Bilbo's Plan gets you a random enemy from the encounter deck for your troubles, and hopefully its threat is high enough to target a location you want to discard (so most likely won't work on high-threat locations). Distant Stars requires the location to be active already, so either you paid the travel cost or used some other card to get the active location where it is. Plus, Distant Stars won't lower the threat in the staging area, so it has a different, but still valid, use case than Heirs of Earendil. Eryn Galen Settler requires you to discard it, which isn't too steep a cost all things told, but also requires the location you're targeting to be the same title as the (explored) active location, which means you have to deal with at least one of those locations in a more conventional way.

Now why would you want to discard a location in the staging area? There are the obvious benefits, those that are shared by exploring a card in the staging area via Northern Tracker or Asfaloth, etc, such as reducing the threat in the staging area and avoiding bad travel costs, but then there are some unique benefits, like being able to get rid of locations with "cannot have progress while in the staging area", discarding cards with X printed quest points like Hills of Wilderland (because printed X = 0), and discarding locations with nasty when explored effects like Sinister Dungeon. And if there aren't any of those sorts of locations in the scenario you're playing, it's still very good location control.

Now, the costs. The major one, a unique Noldor and a unique Dúnedain character. Aragorn and Arwen are what immediately jump to mind, but there are plenty of combinations that are possible here. Now, if you're going for a purely Noldor or Dúnedain deck, those combinations probably won't be utilized, but this card is a good reason to build a deck with these traits, and Tale of Tinúviel is a fun reason to do so, even if I struggle to use it well. Next cost, raise your threat by the printed quest points. Considering you must control a unique Noldor character, you have easy access to Elrond's Counsel, and you might even control Aragorn, so this is a cost that's rarely impactful, though there do exist some nightmare locations to give you pause (looking at you, Gladden Marshlands).

So, there you go. Use the guidance of the great mariner Eärendil and the Silmaril he bears across the sky to just skip over some location entirely.