Noldor decks are well known for their constant discarding, and their cost reduction is no different. The cost of discarding a single card is pretty comparable to spending a single resource, which on the surface makes it look like you have done a one-for-one trade, but there are plenty of ways to swing this trade in your favor.

Want to power up Sailor of Lune? Discard an event as you play him (or any ally) for one less resource. Want to make ally Glorfindel cheaper? Discard him from your hand and then play him from the discard for cheaper. Elven-light wants to be in the discard pile anyways so may as well throw that in too. Anchor Watch, Elwing's Flight, The Evening Star, Skyward Volley, and Veteran Sword-elf all get more powerful when there are copies of themselves in the discard. To close I would like to point out that in an Erestor deck this card is especially helpful since you will be discarding any cards you don't use at the end of the turn anyways, so you may as well chuck 'em now for some juicy cost reduction.

I don't play Noldor decks often but when I do this card is in my decklist. 10/10 would yeet Glorfindel for money again.