If a Guest Seat is available and you call EY Guest you can avail of the mileages shown on the mileage chart online, and should be able to use the ADCB voucher too.
For AUH-ICN the miles are between 35,111 to 114,667 depending on the original economy booking class.
These only apply if the Guest Seat is available, which is unlikely the closer you get to the departure date.
I have successfully upgraded this way AUH-MAN and DUB-AUH already this year.

If you ask at the airport the prices/miles required are usually astronomical, even with EY Guest Platinum 50% discount.