Cost: 1. XP: 2.

Elige una carta de tu zona de juego o revela una carta de tu mano. Busca en tu mazo otra copia de esa carta y róbala. Baraja tu mazo.

"…toda la vida no es más que un conjunto de imágenes existentes en nuestro cerebro, sin que se dé diferencia alguna entre las que nacen de las cosas reales y las engendradas por sueños que solo tienen lugar en la intimidad…" - H. P. Lovecraft, "La llave de plata"
Romana Kendelic
El lado oscuro de la luna #205.
Sueño lúcido

For everyone's benefit, here is a list of the cards that most obviously synergies with Lucid Dreaming (as of Dream Eaters). Please mention any that I miss out in the comments:

Signature Cards:

Stack-able Hand Assets:

Disposable/Temporary Assets With Persistent Effects:

Most of the Myriad Cards:

Cards That Synergies With Themselves:

And that should about be it. Of course Lucid Dreaming has additional functionality outside of these cards; drawing the second copy of your 5xp sink or your assets with limited uses is always a good thing. And of course, not all of the cards presented are particularly powerful with Lucid Dreaming (e.g. Knife); this list it just a time saver for everyone who wants to know where Lucid Dreaming goes above and beyond a card draw.

Lucaxiom · 1718
a) Yes you can trigger two copies of Survival Knife on the same attack as they are responses on two different cards. b) why would Hot Streak 4 and Expose Weakness 3 not make the list? — slothgodfather · 7
Expose Weakness (3) reduces the fight value of an enemy to zero. A second Expose Weakness (3) would also reduce the fight value to zero, AKA make no change at all. As for Hot Streak (4), I'll admit my reasoning is quite tenuous; essentially, you won't really need one copy of Hot Streak (4) to trigger another copy, as the cost of 3 resources is affordable. Hot Streak (2)'s 5 resource cost will generally need assistance from another economy card; it doesn't have to be another copy of itself, but it can be, and thus is included on this list — Lucaxiom · 1718
I think it's also quite good for various Talent Assets which you are allowed to have 2 copies of in play. I was thinking cards like Pathfinder, Fieldwork, Drawing Thin, High Roller, Pickpocketing, Well Prepared, etc. Whether it's really worth 2XP, and 1 Action/Card/Resource just to draw the 2nd copy remains to be seen. — Faranim · 246
In anyone with seeker card access, the full-deck-search means a guaranteed Astounding Revelation trigger (or Occult Evidence, if you're Mandy), which is significant value. And of course, Mandy can run this to grab the 2nd & 3rd copies of Segment of Onyx with her special ability, which is pretty rad. — NatesPromNight · 470
It also guarantees a Shocking Discovery trigger for Mandy, if she hasn't dealt with that yet. — CSerpent · 76
You missed out Dream-Enhancing Serum, which will draw you a second card as you reveal both because Lucid Dream specifies its a card draw to which you can react. — The_Wall · 172
Your discard pile is also in your play area. — Dis · 1
@Dis: Nope. Discard piles are specifically out-of-play areas, which are contrasted to players' play areas, which are (logically enough) in-play areas. See "In Play and Out of Play" (and "Discard Piles") in the Rules Reference. — Tamsk · 1
I'm not a huge fan of Empower Self, really. But at least you can find the other versions with one of them in hand/play and Lucid Dreaming. Although it's making a slow, expensive and clunky card even slower, more expensive and more clunky. — olahren · 595