Using a d20 for skill checks has excess granularity. The d12 works perfectly for me, because I was able to come up with a common-language description for each number on the die which is siginificantly different enough from the descriptions of its neighboring numbers. Using a d20 scale, I would see no difference between assigning a DC of, say, 13, or assigning a DC of 14. Using a d12 also scales well with my maximum +8 in bonuses.
I'm playing with a very leisurely pace of leveling up, and with a max character level of 12, and a max skill/talent bonus of 8, leveling up and an incremental skill increase should show a marked improvement in abilities. Going the other way - fast-paced level increases with high maximum levels and higher max skill bonuses, just seems like adding busy work book-keeping to the game. That +1 you get to a d20 skill check doesn't feel like anything. I prefer the satisfaction of being noticeably better at something today than I was last week as opposed to the arguably illusory verisimilitude of constant small-increment progression.
Level
|
Skill Bonus
|
1
|
1
|
2
|
2
|
3
|
3
|
4
|
3
|
5
|
4
|
6
|
4
|
7
|
5
|
8
|
5
|
9
|
6
|
10
|
6
|
11
|
7
|
12
|
7
|
13
|
8
|
Average Joe
|
No training and no talent
|
+0
|
Apprentice/ Advanced beginner |
Strong talent or basic training
|
+2
|
Journeyman
|
Advanced training and some talent
|
+4
|
A top guy in the field
|
Nearly nothing left to learn & strong talent
|
+6
|
Ultimate master
|
It will be centuries before we see her like again. Max skill (+6) and max talent (+2)
|
+8
|
% to meet or beat DC
|
DC
|
Any old shlub
|
Apprentice
|
Journeyman
|
A Top Guy
|
Ultimate Master
|
|
100%
|
1
|
|||||
|
92%
|
2
|
Should be child's play, but a fumble is still possible
|
||||
|
83%
|
3
|
This is nearly routine for me
|
||||
|
75%
|
4
|
The smart money's on my success
|
Should be child's play, but a fumble is still possible
|
|||
|
66%
|
5
|
I'm getting good at this
|
This is nearly routine for me
|
|||
|
58%
|
6
|
Let me show you how it's done (humble)
|
The smart money's on my success
|
Should be child's play, but a fumble is still possible
|
||
|
50%
|
7
|
Even odds
|
I'm getting good at this
|
This is nearly routine for me
|
||
|
42%
|
8
|
Let me show you how it's done (arrogant)
|
Let me show you how it's done (humble)
|
The smart money's on my success
|
Should be child's play, but a fumble is still possible
|
|
|
33%
|
9
|
It's not easy, but let me have a shot at it
|
Even odds
|
I'm getting good at this
|
This is nearly routine for me
|
|
|
25%
|
10
|
Difficult
|
Let me show you how it's done (arrogant)
|
Let me show you how it's done (humble)
|
The smart money's on my success
|
Should be child's play, but a fumble is still possible
|
|
17%
|
11
|
Formidable
|
It's not easy, but let me have a shot at it
|
Even odds
|
I'm getting good at this
|
This is nearly routine for me
|
|
8%
|
12
|
Hail Mary
|
Difficult
|
Let me show you how it's done (arrogant)
|
Let me show you how it's done (humble)
|
The smart money's on my success
|
|
---
|
13
|
Formidable
|
It's not easy, but let me have a shot at it
|
Even odds
|
I'm getting good at this
|
|
|
---
|
14
|
Hail Mary
|
Difficult
|
Let me show you how it's done (arrogant)
|
Let me show you how it's done (humble)
|
|
|
---
|
15
|
Formidable
|
It's not easy, but let me have a shot at it
|
Even odds
|
||
|
---
|
16
|
Hail Mary
|
Difficult
|
Let me show you how it's done (arrogant)
|
||
|
---
|
17
|
Formidable
|
It's not easy, but let me have a shot at it
|
|||
|
---
|
18
|
Hail Mary
|
Difficult
|
|||
|
---
|
19
|
Formidable
|
||||
|
---
|
20
|
Hail Mary
|
||||
% to meet or beat DC
|
DC
|
Any old shlub
|
Apprentice
|
Journeyman
|
A Top Guy
|
Ultimate Master
|
Class levels are used for contested rolls instead of the Skill Rating which is used for DC skill checks. If the skill involved for an opposed roll is a skill which fits the class of the contestant, then the bonus applied is the contestant's level. If the skill does not fit with the contestant's class, then apply half of that contestant's class as their bonus. Note that the skills used by the attacker and defender are not necessarily the same skill. If a rogue tries to sneak past a guard, then the rogue is using a thief skill, so his full level as applied as a bonus. If the guard is a trained sentry, then her full level should be applied to her roll. However, if the guard is a cavalry woman temporarily assigned to this guard post, then I would only apply half of her level as a bonus to her roll.
For opposed rolls, skill should count for much more than luck does. Given that my max level will only be 12, I need to use the smallest die I'm willing to roll (I don't like d4s), so I use the d6 for the random element of character vs character contests. To bias the results away from the extremes, each contestant rolls 3d6 and takes the middle value. I ran the numbers for d8 and d12 too when I was exploring my options, and since I'm an information hoarder, I'm leaving those tables here.
Chance the Attacker wins with the following Attacker vs Defender bonus differences (tie goes to defender)
3d6, take the middle:
Bonus difference
|
Attacker Success Rate
|
-6
|
0%
|
-5
|
0%
|
-4
|
0.5% (auto failure)
|
-3
|
3%
|
-2
|
10%
|
-1
|
23%
|
0
|
40%
|
1
|
60%
|
2
|
77%
|
3
|
90%
|
4
|
97%
|
5
|
99.5% (auto success)
|
6
|
100%
|
3d8, take the middle:
Bonus difference
|
Attacker Success Rate
|
-8
|
0%
|
-7
|
0%
|
-6
|
0.1%
|
-5
|
1% (auto failure)
|
-4
|
4%
|
-3
|
9%
|
-2
|
17%
|
-1
|
29%
|
0
|
43%
|
1
|
57%
|
2
|
71%
|
3
|
83%
|
4
|
91%
|
5
|
96%
|
6
|
99% (auto success)
|
7
|
99.8%
|
8
|
100%
|
3d12, take the middle
Bonus difference
|
Attacker Success Rate
|
-12
|
0% (auto failure)
|
-11
|
0% (auto failure)
|
-10
|
1% (auto failure)
|
-9
|
1% (auto failure)
|
-8
|
1% (auto failure)
|
-7
|
2% (auto failure)
|
-6
|
4%
|
-5
|
8%
|
-4
|
13%
|
-3
|
19%
|
-2
|
27%
|
-1
|
35%
|
0
|
45%
|
1
|
55%
|
2
|
65%
|
3
|
73%
|
4
|
81%
|
5
|
87%
|
6
|
92%
|
7
|
96%
|
8
|
98% (auto success)
|
9
|
99% (auto success)
|
10
|
99% (auto success)
|
11
|
99% (auto success)
|
12+
|
100% (autosuccess)
|