Another for the list of Radnorshire-disputed-antiquity-stones I fear. From “The Ancient Stones of Wales” by Chris Barber and John Godfrey Williams:
“A standing stone in the centre of a field called Maes y Garreg on Pontycaragh farm (SO200791). It resembles a battered human face and is 5 feet high. It is marked as Standing Stone on Ordnance Survey map of 1947. R.C.A.M. No. 80 of Radnor. One local story is that the Devil threw the stone from his chair at Craig y Don near Knighton, Radnor, aiming it at Beguildy Church, but it fell short by half-a-mile and the stone is still supposed to bear Satan’s fingerprints.”
Coflein supposes the stone to be natural:
coflein.gov.uk/en/site/306395/details/OLD+STONE%3BPANT-Y-CAREGL%2C+STONE/