How do you handle Wish?

[KorvinStarmast]

I have one. I don't remember what it was for, but I used it back in the AD&D days.

You can roll a d30 by rolling a d6 and a d10 at the same time.
die result of the d6 1,2: d10 roll is as it shows.
die result of the d6 3,4: add 10 to d10 roll result
die result of the d6 5,6: add 20 to d10 roll result.