MENTAL Spells which produce a wide range of magical effects are known as mental spells. Some equipment can help one to better resist the affects of these spells, causing the spell to fail. Also, those who are more intelligent can better understand the workings of such spells, and therefore better avoid its effects. Notable mental spells include summon and dispel magic. Illithids, giants and minotaurs experience a bonus (or penalty) to casting mental spells based on their present intelligence stat. This is equal to their current (intelligence-20)/2, rounded down.
11.8.3. SUMMARY > COMBAT > MAGIC > MENTAL