They have such a power spell and deadly attack, hell all i can see was *boom* then i got frozen like ice then they took my brain and hit me a few times, then i am gone ... not even count the damn Humber (something) they also do a great damage.

Can i use a special spell or something to prevent "stun" or "panic" spell?

thanks

Chaotic Commands prevents you from being stunned or dominated, but nothing you can do will prevent them from using their brain devour. Don't face them in toe-to-toe combat. There are a few methods for dealing with the illithid, all complicated and usually annoying. The first is to use a thief with some invisibility potions to backstab them. The second is to summon certain creatures which don't have any intelligence anyway, so they can't be brain devoured.