D&D 1E a system to purchase special abilities and skills

[le Redoutable]

it says that
1° you have a base cost
2° you have a level of mastery

to find the actual xp cost of your skill or ability ( s_o_a ) you add Base Rank ( b r ) to level of mastery ( l m ) and refer to Global Rank ( G_R )

Spoiler: s_o_a cost based on Base Rank + Level of Mastery

G_R cost
-10 1
-9 2
-8 4
-7 8
-6 15
-5 30
-4 60
-3 125
-2 250
-1 500
0 1k
1 2k
2 4k
3 8k
4 15k
5 30k
6 60k
7 125k
8 250k
9 375k
10 500k
11 625k
12 750k
13 875k
14 1M
15 1.125M
16 1.25M
17 1.375M
18 1.5M
19 1.625M
20 1.75M
21 1.875M
22 2M
23 2.125M
24 2.25M
25 2.375M
26 2.5M
27 2.625M
28 2.75M
29 2.875M
30 3M

the actual base cost of any s_o_a varies from -6 + L_M for a Thief's abilities, to a -2 + L_M for a bonus to THAC0;

example with THAC0:

you wish to have a +7 to your THAC0;
it will cost you -2 +7 =+5 ===> 30k xp

using Fighter's xp table, a Fighter of 7th Level has got 64k xp ( that I drop to 60k );
so a +7, which looks like a THAC0 of a 7th Level Fighter, requires half of the xp that this character owns;



as usual, the skeleton is good, then specialists ( if got involved ) should balance things a bit

because of course the Fighter above needs Hit Points, Extra Attacks etc