If you want to roll, we roll 4d6 down the line, with an extra 4d6, which can replace any one of the first six rolls.
For example, six 4d6 rolls down the line: 14, 13, 8, 14, 15, 12
Extra 4d6 roll: 13
The 13 can be used to replace the 8, for 14, 13, 13, 14, 15, 12, in order.
Otherwise, you can...