#### Mercurius

##### Legend

I'm trying to do some research and understand the underlying mathematics of 4E, somewhat similarly to Trailblazer's "the Spine." Specifically, right now I'm looking at attacks vs. AC and Defenses at different levels, taking into account Ability mods + half level bonuses, as well as relevant likely enhancements. After a year+ of light play, I feel like I am only finally entering the "intermediate" stage of understanding the rules, so please let me know if I am missing anything.

As far as I understand it, each defense is composed of:

I'll leave aside situational modifiers for now, including relevant feats that improve Defenses in very specific circumstances.

Which brings me to:

1st: 10 to 18 (base 10 +1 enhancement +5 Ability mod +2 class bonus)

5th: 12 to 20 (base 12 +1 EB +5 AM +2 CB)

10th: 15 to 25 (base 15 +2 EB +6 AM +2 CB)

15th: 17 to 29 (base 17 +3 EB +7 AM +2 CB)

20th: 20 to 33 (base 20 +4 EB +7 AM +2 CB)

25nd: 22 to 38 (base 22 +5 EB +9 AM +2 CB)

30th: 25 to 43 (base 25 +6 EB +11 AM +2 CB)

Armor Class would be approximately the same.

So am I missing anything?

EDIT: I added Prophetic Blessing into the Ability Modifier.

As far as I understand it, each defense is composed of:

**Base Defense + Enhancement bonus + Primary Ability Modifier + Class bonus**

*Base Defenses:*10 + Half Level*Magical Enhancement bonuses:*+1 at 1st, +2 at 6th, +3 at 11th, +4 at 16th, +5 at 21st, +6 at 26th.*Maximum Primary Ability Modifier:*1st level +5; 8th level +6; 14th level +7; 21st level +8; 28th level +9.*Class bonuses:*0 to +2I'll leave aside situational modifiers for now, including relevant feats that improve Defenses in very specific circumstances.

Which brings me to:

**Defense Ranges by Level (assuming level appropriate magic items):**1st: 10 to 18 (base 10 +1 enhancement +5 Ability mod +2 class bonus)

5th: 12 to 20 (base 12 +1 EB +5 AM +2 CB)

10th: 15 to 25 (base 15 +2 EB +6 AM +2 CB)

15th: 17 to 29 (base 17 +3 EB +7 AM +2 CB)

20th: 20 to 33 (base 20 +4 EB +7 AM +2 CB)

25nd: 22 to 38 (base 22 +5 EB +9 AM +2 CB)

30th: 25 to 43 (base 25 +6 EB +11 AM +2 CB)

Armor Class would be approximately the same.

So am I missing anything?

EDIT: I added Prophetic Blessing into the Ability Modifier.

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