Striped wheel nut.

[Pastrykiller]

12 pt 13mm socket and hammer. Works most

[mother trucker]

take a hand grinder or a file and put flat surface back on the nut us vise grips after u can get a good grip on it

if this doesn't work grind the nut of completely off along with the bolt then knock the bolt out of the wheel hub and buy a new bolt for the hub and replace it and your set