[Agema]

With 10MR, illithids paralyze with just under 50% effectiveness. At 14MR, they would paralyze with just over 10% effectiveness. (It's also worth bearing in mind it's not just the paralyze, but the 1AN MR damage over time causes enormous damage as well.)

If 50 illithids faced 50 arrsatuts with 10MR, virtually the whole squad would be paralyzed in a few turns. With 14MR, by the time the illithids had paralyzed half the arrsatuts the first paralyzed would be about to recover.