Slippery 8 Loop
This adjustable loop was described to me by Dave Poston and probably was discovered by him. It has surprising security for an adjustable loop and has the unique feature that the loop cannot possibly contract under tension should extraordinary circumstances cause it to slip.
One extraordinary circumstance to avoid is having the legs of the loop at a 90 degree angle or greater when under tension. Having the legs at an angle greater than 90 degrees puts the Slippery 8 into its adjustable mode. This knot depends on having the end of the rope "turn the corner" for its security, so don't sabotage it.
Thanks, Dave, and let us know the formal name of your creation when you decide upon it.