I suddenly realized that a straight set of bonus adds to defenses won't work.
Take the following example:
Same level creature to hit number against: high defense (taken every time plus starting stat 18 plus 2 class), medium defense (taken every other time plus starting stat 14 plus 1 class), low defense (never taken plus starting stat 10 plus 0 class): assuming item gain at levels 3, 8, 13, 18, 23, 28 and not using feats or race bonus and creature is Level +4 against the defense (most monsters average level +3 to level +5 except the Brute).
Code:
1 11 8 5
2 11 8 5
3 11 8 5
4 11 8 5
5 10 7 4
6 10 7 4
7 9 6 3
8 11 7 4
9 10 6 3
10 10 6 3
11 9 6 2
12 9 6 2
13 9 6 2
14 10 6 2
15 9 5 1
16 9 5 1
17 8 4 0
18 9 5 1
19 9 5 1
20 8 4 0
21 8 4 0
22 8 4 0
23 8 4 0
24 8 4 0
25 7 3 -1
26 7 3 -1
27 6 2 -2
28 8 3 -1
29 7 2 -2
30 7 2 -2
As can be seen, the difference between best and worse defense at level 1 is 6. At level 30, it's 9. There is no linear way to balance the two because PCs will almost always have a large delta between best and worse and will also often face higher level monsters. At high levels, some PCs will almost always get hit on a 2 and only missed on a 1 versus one or two of their defenses (with core rules).
The delta between best and worse has to be decreased for any bonus math to work.
One example of a solution:
Every defense = average round down of best defense and itself plus add +1 at levels 11, 16, 21, and 26. Non-core feats (like Epic Iron Wind) not allowed.
So, a PC at level one with defenses 16, 14, and 11 would instead have 16, 15, and 13. His same level foes are typically +5 to hit.
A PC at level 30 with defenses 41, 36, and 32 would instead have 45, 42, and 40. His same level foes are typically +34 (or better). Higher level foes are typically +37 or +38 (against low to mid-40 ranges, synergy and paragon feat bonuses are still needed).
This changes various sections of the chart to:
Code:
1 11 9 7
11 10 8 6
21 10 8 6
30 11 8 6
Delta of 4 at level one, delta of 5 at level 30. The best defense is still the best. The worse is still the worse. It's just that the non-best defenses do not fall off the bottom of the D20.
And remember, this is for a same level creature.
But, the real problem here is how large the delta between a good defense and a bad defense starts out and how much greater it can become. 9 is a big chunk of a D20.
Note: Some DMs might feel more comfortable with +1 at 5, 15, and 25 instead of +1 at 11, 16, 21, and 26.
What do you think of this Elric?