This only confirmed possible on xbox. But PC users and use cheats anyways.
I saw a youtube video on this, if you are Hero rank in the arena you will eventually have to fight a guy who uses a shield called the Gray Aegis, which give 100% magic resistance. In order to do this you need the Staff of Worms and the Skull of Corruption. Check the wiki to see how to get those.

Start the fight and do NOT attack him at all, stay near him so he keeps hitting you with his sword. (He has terrible blade skill so it doesn't hurt more than maybe 10 hp) Let him keep hitting you until his weapon breaks. (Before you ask, Disintegration spells do not work, remember he has the Gray Aegis.)

After his weapon breaks you can kill him and he wont drop his shield. Kill him, then reanimate him with the Staff of Worms. Then quickly clone him with the Skull of Corruption. Now kill the clone only. As soon as the clone dies, move your cursor over the body and save. Then reload the file and keep pressing A while its loading. You will end up in the clones inventory which has the Gray Aegis, and the Yellow team Raiment as a little bonus.

Best shield in the game, blocks all magic besides your own so you can still heal yourself and stuff. You don't need to block for the effect to work in case you're wondering. Recommended for High Elf characters highly, They have More magic and more weakness to it i'm pretty sure. With this its just more magic.