Similes of Attainment

Though to the extent of my admittedly scarce knowledge, decapitation as a simile for some level of attainment is not to be found in the Pali Canon, but I bet the Zen tradition offers countless koans and stories wherein, figuratively, the incumbent experiencer of realization is beheaded, very much to his surprise I would say. If you happen to know a few of these stories, your kind attention in helping me digging out these similes is greatly appreciated. My gratitude for having taken the time to read this.