TA-TA-TATA GRAND FIRST POST!
For cheaters, use the change traits cheat and change your sim´s traits to coward, clumsy, unlucky, loser, and grumpy and you will lose the fights against mummies
. I recomend to save before encountering a mummy to make sure if you doesn´t get cursed the first time, you can try until you get it. For normal players, purchase the mid-life crisis reward to change traits for 20,000 lifetime happiness points and other 20,000 to change your original traits back.
My sim is level 6 on 7 martial arts so I don´t know if it will work on a level 10, but I hope I helped!