I put together one more set of statistics from the Monster Manual -- some information about monster attacks. These statistics count every listed attack equally, whether it's at-will, encounter, recharge, etc. I've updated the original MM statistics post to include these new tables.
The first table shows what percentage of creatures at each tier have at least one attack that targets each defense. For example, only 13.8% of level 1-10 creatures have an attack that targets Will. "AC only" is the percentage of creatures that have an attack against AC and not against any other defenses.
Attacks against AC are the most common (no surprise), and attacks against Will are the least common, with only about 21% of creatures having an attack vs. Will. At higher tiers, we see more creatures able to attack defenses other than AC.
The next table shows the average attack bonus vs. each defense, compared to the creature's level. For example, level 1-10 creatures have an average attack vs. AC of their level + 4.47. These say pretty steady; attacks against AC are at level + 4-5, and attacks against other defenses are at level + 3.
The first table shows what percentage of creatures at each tier have at least one attack that targets each defense. For example, only 13.8% of level 1-10 creatures have an attack that targets Will. "AC only" is the percentage of creatures that have an attack against AC and not against any other defenses.
Attacks against AC are the most common (no surprise), and attacks against Will are the least common, with only about 21% of creatures having an attack vs. Will. At higher tiers, we see more creatures able to attack defenses other than AC.
Code:
1-10 11-20 21-30+ Overall
AC 95.6 96.3 86.5 94.5
Fortitude 24.9 35.3 43.2 31.7
Reflex 25.8 37.4 55.4 34.8
Will 13.8 26.3 28.4 20.9
AC only 51.1 34.2 27.0 40.9
Code:
1-10 11-20 21-30+ Overall
Attack vs. AC - Level 4.47 4.41 4.55 4.46
Attack vs. Fortitude - Level 3.15 3.15 3.07 3.13
Attack vs. Reflex - Level 3.14 3.01 2.95 3.03
Attack vs. Will - Level 2.97 3.39 2.75 3.13