You could play this card while your threat is over 20, but then you would just be Swift. Or, you could play this card while all your heroes are ready, but then you would just be Silent. Also, this card sure takes a long time to read for something called Swift and Silent. You should probably Just use Cram instead.
Swift and Silent
Event.
Cost: 1.
Action: Ready a hero you control. Then, if your threat is 20 or less and this is the first time you played a copy of Swift and Silent this round, return this card to your hand instead of discarding it.
A marching host of Elves had come up silently... The Fellowship of the Ring
Raymond Bonilla
The Dunland Trap #3 Leadership.
Reviews
Got a little new lease of life with The Grey Wanderer and Council of the Wise, however this is still a hard sell. As a one-time use, this is simply not good enough when compared to cards like Cram, and if you want to use it repeatedly, there is a) the condition of staying below 20 threat and b) once more the competition, with cards like Unexpected Courage, Armored Destrier or even Heir of Mardil being a lot more efficient resource-wise in the long run. A very niche card at best, maybe just making the cut in some select few decks but not a very attractive proposition overall.
Rating: 2.5/10
Decks of mine using Swift and Silent