A great submission that really deserves more plot ideas then it has. I could see an entire campaign around this organization - perhaps as an employer or an enemy, or a third party in a more complex scenario.
I like this - a cross between the Lonely Mountain and Everest. Perhaps one could even make it such that the mountain has gotten higher over time - much faster than normal - making its hazard much greater than when the dwarves dwelled there. Go to Comment
I like this - it could even work as a form of one-time-pad, which is nearly unbreakable.
Another feature would be the knots and such must be unraveled to be read, making it almost impossible for the message to be intercepted, read, and then passed on. This is a big deal since not receiving the expected message, or one with signs of tampering can warn someone. Go to Comment
I think this is an excellent idea, though it depends upon your magic being loose enough to accept this. Some fictional (aren't they all) examples of circle use are so exacting as having a hair drop across a line is sufficient to blow the protection. With such standards, a carpet would be play Russian roulette with 5 rounds loaded.
For D&D though, or lower-stakes magic, I see this as perfectly fitting. Go to Comment
If a creature is transformed into another creature (say, a human into a dog), then that creature will become more and more accustomed to the new form until a point is reached where reversing the spell is impossible. A second transformation is possible, but the creature will have to go through the whole process again.