at (one's) own peril
Done with the foreknowledge or forewarning that there is implied danger, especially of loss of life, which one must accept as one's own responsibility. Those who skydive do so at their own peril.
(do something) at your (own) ˈperil
(often used as a warning) at the risk of serious danger: People who go climbing in winter do so at their own peril.You go in Mike’s car at your peril. He’s a terrible driver.fraught with danger/peril
Very risky indeed. Fraught with means “full of ” and is rarely used today except in the sense of something undesirable. The expression, a cliché since the nineteenth century, first appeared in print in 1576 as “fraught with difficulties”; the precise cliché was first cited by the OED as appearing in 1864 in H. Ainsworth’s Tower of London: “This measure . . . is fraught with danger.”