Converting Immortals Ability Scores
by Bruce HeardFor all creatures that are described in the AD&D(R) Game, standard monsters in particular, simply use the ability scores given in the AD&D Game (don't bother with conversions there). For all the others various conversion systems are possible. One is a simple math conversion of the abilities, regardless of the adjustments they imply. The other, far more complicated, involves rough comparisons between the effects of ability adjustments of the two games.
STRAIGHT SCORE CONVERSION: Simply assume that scores of 1-18 are the same in both games. That leaves 19-25 for the remainder of the D&D Game ability scores, as follows:
| 19 | 19-30 |
| 20 | 31-42 |
| 21 | 43-54 |
| 22 | 55-66 |
| 23 | 67-78 |
| 24 | 79-89 |
| 25 | 90-00 |
Of course the problem with this is that an Immortal with a
Strength of 100 used to have a +20 adjustment to both attack
and damage scores (not the +7/+14 adjustments of the AD&D
Game's maximum Strength of 25).
For your typical PC or monster, this probably doesn't matter
much, but if you plan on using the Immortals system with the
AD&D Game, these ratings won't work.
AJUSTMENT CONVERSION: In this case, you have to come
up with separate conversion tables for each set of ability scores
since the AD&D Game offers completely different adjustments
for each one.
For Strength, you'd need to average out attack/damage
adjustments and compare them to the D&D Game's standard
ability adjustment. For Dexterity, you could average out missile
attack and defensive adjustments and use that as a basis for the
comparison, etc.
For example, the AD&D Game Strength Table shows a
+7/+14 for a Strength of 25. The D&D Game offers instead
single adjustments ranging from +7 to +14 for various Strength
scores. I'd hit that one in the middle and consider the D&D
Game equivalent adjustment to be +10. So a Strength rating of
25 in the AD&D Game would be equivalent to a rating of 46-53
in the D&D Game.
Beyond this score, we end up with creatures stronger than
gods in the AD&D Game. There's no way to avoid that. For
scores that would end up above the AD&D Game's maximum
of 25, use a new rating, much like fighters with Strengths in the
upper 18's! Having established that conversion milestone, we
can now develop the first conversion table, as follows:
| Strength | |
| AD&D Rating | D&D Rating |
| 1 | 1 |
| 2 | 2-3 |
| 3 | 4-5 |
| 5 | 6-7 |
| 6-7 | 8 |
| 8-9 | 9 |
| 10-11 | 10 |
| 12-13 | 11 |
| 14-15 | 12 |
| 16 | 13 |
| 17 | 14-15 |
| 18 | 16 |
| 18/01-50 | 17 |
| 18/51-75 | 18 |
| 18/76-90 | 19 |
| 18/91-99 | 20 |
| 18/00 | 21 |
| 19 | 22 |
| 20 | 23 |
| 21 | 24-27 |
| 22 | 28-32 |
| 23 | 33-38 |
| 24 | 39-45 |
| 25 | 46-53 |
| 25/01-25 | 54-62 |
| 25/26-45 | 63-70 |
| 25/46-60 | 71-77 |
| 25/61-72 | 78-83 |
| 25/73-82 | 84-88 |
| 25/83-89 | 89-93 |
| 25/90-94 | 94-96 |
| 25/95-97 | 97-98 |
| 25/97-99 | 99 |
| 25/00 | 100 |
Of course, this does mean that you should check all the AD&D
Game's greater gods with ability scores of 25. Whenever they
come into play, I would suggest rolling percentile dice to find
out how far up the 25's these abilities really get. Incidentally,
this would really help differentiating lesser from greater gods.
Of course, nothing prevents anyone from counting a score of
25/01-25 as a "26", and 25/26-45 as "27" instead -- and so forth
all the way up to "35". But at least, the percentile system allows
you to quickly roll up stats if you ever need them.
Now all you need to do if follow a comparable route for the
other five ability tables!