Elrond's Counsel is one of the best threat reduction effects in the game. It costs zero and the little willpower boost is always helpful. The fact that you must control a unique Noldor character can be a slight problem, but the pure efficiency of Elrond's Counsel more than makes up for the extra deck construction.
Action: If you control a unique Noldor character, give another character +1 until the end of the phase and lower your threat by 3.
Elrond, The Fellowship of the Ring
The Watcher in the Water #59. Spirit.
After buying the Watcher in the Water and trying it out, I can say with certainty that my pre-purchase thoughts about the card were correct;
1) 0 cost threat reduction is ridiculously good.
2) The "additional cost," like the additional cost to play Knight of the White Tower, is so trivial that it feels wrong to even call it a cost; Elrond's Counsel requires you to control unique Noldor characters, like some of the best characters in the game. This is like making an absurd event that requires you to control a Gondor hero to play: do we really need to be incentivized to include Steward of Gondor?
3) The boost is simply gravy, piled high on an already enormous meal; several times, I've simply played it during the planning phase to get a secrecy discount.
Overall, Elrond's Counsel is disgusting, like Warden of Healing; unfairly cheap and egregiously efficient, they are the cards you will love to hate. They're like the Ring, toxic over the long term (how many healing cards had their careers cut short because they weren't as devastatingly efficient as Warden?) but tempting in the short term. You will use them, you will learn to rely on them, and it will take a supreme act of will in order to put them down once you've picked them up.