The Ouroboros Knot
This particular occult method of tying a tie mostly resembles a Trinity Knot, with two differences. The first is that the tie is given one twist in the back, to make it something not entirely unlike a Mobius Loop (ties used for Ouroboros Knots are typically the same color on both sides, in order to disguise this). The second difference is the large amounts of magical energy that are pumped into the tie as the Knot is being tied. When correctly done, the Ouroboros Knot is activated and will hold its ‘charge’ for at least a week.
What does the Ouroboros Knot do? Mostly it makes sure that curses don’t connect on the wearer: the mystical pattern defined by the Knot generally forces the curse away from the target’s body and right into the ground. This can happen indefinitely for minor curses, and a few times for serious ones — but even a potent curse can be deflected once this way, although it wrecks the spell until the Knot can be re-tied.
Unfortunately, a curse that’s been deflected typically ends up contaminating the ground underneath the target, which is why this technique is not used as often as one might think. There are a remarkable number of curses flying around at any given time; and most human beings have a sufficiently vigorous occult immune system to shrug them off. Someone who routinely wears an Ouroboros Knot around the office or house will soon find that his home or work environment is getting steadily psychically worse; it’s better to save this trick for times when one really needs it.