Suppose that someone seized my seed with a phrase of 12 words. I deliberately changed the order of words in a phrase in such a way that the only way to get a real phrase is to go through all the possible combinacies of the current 12 words.
1) How many combinations will it be necessary to go through an attacker in order to find a real seed? How long can it take?
2) Do you find such precaution really effective?