Base Attack Bonus and BECM D&D
by KhedracA useful previous thread is Ascending AC /Ascending Saves Saves.
I have come back to this topic because I am expecting to run some BECM D&D with a group used to 3.5 later this year (this way they don't need to learn another system which would cause several players to drop out).
I'll admit, I haven't played BECM D&D for so long that using a lot of 3.5 mechanics will be easier for me too.
As discussed in the previous thread converting BECM AC to an Ascending AC is simple - if using the "10+ modifiers" model just subtract from 19 as previously stated - and this allow us to look at a Base Attack bonus system.
So, assume Ascending AC = 10 + armour modifiers = 19 – descending AC.
Let's ignore the repeats at *10, 2, 20, 30 etc. for now - I will address them after seeing if we can derive a working BAB model.
So - starting by analysing the Combat table we get the following result, here "AB" = "Attack Bonus" (not yet "Base" as it is not derived from levels).
| MU | C, T, D | F | DH | AB |
| normal | man | –1 | ||
| 1-5 | 1-4 | 1-3 | 1-3 | +0 |
| 6-10 | 5-8 | 4-6 | 4-6 | +2 |
| 11-15 | 9-12 | 7-9 | 7-9, A | +4 |
| B | +5 | |||
| 16-20 | 13-16 | 10-12 | 10-12, C | +6 |
| D | +7 | |||
| 21-25 | 17-20 | 13-15 | E | +8 |
| F | +9 | |||
| 26-30 | 21-24 | 16-18 | G | +10 |
| H | +11 | |||
| 31-35 | 25-28 | 19-21 | I | +12 |
| J | +13 | |||
| 36 | 29-32 | 22-24 | K | +14 |
| L | +15 | |||
| 33-35 | 25-27 | M | +16 | |
| 36 | 28-30 | +18 | ||
| 31-33 | +20 | |||
| 34-36 | +22 |
So:
Magic Users need a progression that will hit +14 at level 36.
Cleric, Thieves and Druids need a progression that will hit +18 at level 36*
Fighters need a progression that will hit +22 at level 36
Demi-humans need a progression that will hit +4 at level 8 and +6 at levels 10 and 12.
Attack ranks are easy - full BAB across attack ranks fits perfectly
*Logically Clerics etc should be capping at +16, but since there is a clear break is the sequence to let them hit +18 I will go with +18, but I will offer a +16 solution as well.
Looking at a range of different BAB progression rates we get:
| BAB | @36 | @8 | @10 | @12 |
| 0.65 | +23 | +5 | +6 | +7 |
| 0.6 | +21 | +4 | +6 | +7 |
| 0.5 | +18 | +4 | +5 | +6 |
| 0.45 | +16 | +3 | +4 | +5 |
| 0.4 | +14 | +3 | +4 | +4 |
A BAB of 0.4 is a perfect fit for Magic Users.
A BAB of 0.5 is a good fit for Clerics, Thieves and Druids if you want a +18 cap.
(A BAB of 0.45 is actually a poor fit for a +16 cap as they will lag behind the table at most levels - be nice, go with 0.5.)
And we don't have a good fit for fighters (0.64 is probably the best fit capping at +22) but I will choose 0.65 as not getting "too fiddly" while preserving the fighter's superiority with weapons. The biggest issue with it is that it is not suitable for demi-humans who advance as fighters in Basic and Expert.
Personally I think 0.6 the best fit for demi-humans, though it gives dwarves an extra +1 over elves and halflings (which annoyingly means they will not have the same BAB at the same attack rank).
Monsters are slightly annoying – they are both easier and harder to calculate as they use two different progressions, switching at 10 hit dice.
Up to 10 hit dice they gain +1 per hit die (so BAB = HD–1);
After 10 hit dice they gain +½ per hit die (so BAB = ½HD+4.
Monsters with a bonus to hit points count as the next higher hit dice. For example: a monster with 3+1HD (3HD + 1 hit point) counts as 4HD which is a BAB of +3.
(If you think this is unfair, characters are much more likely to get extra bonuses to hit (e.g. from weapon mastery) than monsters so monsters need the help!)
This gives a combined BAB table:
| Level / Hit Die |
F 0.65 |
DH 0.6 |
C, D, T 0.5 |
MU 0.4 |
HD ≤10 |
HD >10 |
| 1 | +0 | +0 | +0 | +0 | +0 | |
| 2 | +1 | +1 | +1 | +0 | +1 | |
| 3 | +1 | +1 | +1 | +1 | +2 | |
| 4 | +2 | +2 | +2 | +1 | +3 | |
| 5 | +3 | +3 | +2 | +2 | +4 | |
| 6 | +3 | +3 | +3 | +2 | +5 | |
| 7 | +4 | +4 | +3 | +2 | +6 | |
| 8 | +5 | +4 | +4 | +3 | +7 | |
| 9 | +5 | +5 | +4 | +3 | +8 | |
| 10 | +6 | +6 | +5 | +4 | +9 | |
| 11 | +7 | +6 | +5 | +4 | +9 | |
| 12 | +7 | +7 | +6 | +4 | +10 | |
| 13 | +8 | +6 | +5 | +10 | ||
| 14 | +9 | +7 | +5 | +11 | ||
| 15 | +9 | +7 | +6 | +11 | ||
| 16 | +10 | +8 | +6 | +12 | ||
| 17 | +11 | +8 | +6 | +12 | ||
| 18 | +11 | +9 | +7 | +13 | ||
| 19 | +12 | +9 | +7 | +13 | ||
| 20 | +13 | +10 | +8 | +14 | ||
| 21 | +13 | +10 | +8 | +14 | ||
| 22 | +14 | +11 | +8 | +15 | ||
| 23 | +14 | +11 | +9 | +15 | ||
| 24 | +15 | +12 | +9 | +16 | ||
| 25 | +16 | +12 | +10 | +16 | ||
| 26 | +16 | +13 | +10 | +17 | ||
| 27 | +17 | +13 | +10 | +17 | ||
| 28 | +18 | +14 | +11 | +18 | ||
| 29 | +18 | +14 | +11 | +18 | ||
| 30 | +19 | +15 | +12 | +19 | ||
| 31 | +20 | +15 | +12 | +19 | ||
| 32 | +20 | +16 | +12 | +20 | ||
| 33 | +21 | +16 | +13 | +20 | ||
| 34 | +22 | +17 | +13 | +21 | ||
| 35 | +22 | +17 | +14 | +21 | ||
| 36 | +23 | +18 | +14 | +22 |
Attack Ranks are not shows as they are not consistent across the demi-humans, but they have full BAB (+1 per rank).
The Attack Tables for BECM D&D repeat the target number 20 five times before proceeding to 21. Technically this is supposed to mean that not only is a (natural?) 20 required, but a minimum bonus on the attack roll of the amount over 20 is required. In BECM play the chance of encountering something where the attack roll bonus is less than the amount required is effectively zero (consider weapon mastery) so the only real effect is that the armour classes where ‘20’ should repeat are harder to hit; at level 1 these are ACs –2 to –5 (21 to 24 using the ascending system). I consider this unlikely enough that it is not worth factoring into the system. After basic levels, the increase in character attack bonuses from things like weapon mastery offset the need for the repetitions which were introduced in the Companion Rules (or earlier).
Whichever way you look at it, I think the effect on play of ignoring this will be minimal (so the cost of factoring it in outweighs the benefit).
At the other end of the scale, if the target AC is poor enough, the attacker gets bonus damage on their attack. Again technically this has a sequence of repeats in it, again this is only relevant for Immortal level play, so I again we will ignore the repeats.
Bonus Damage = BAB – target’s AC – 4 (minimum 0)
Note - these statements only apply to MORTAL level play. For immortals, where encountering a much wider range of ACs is likely, these assumptions fail, but I don't think D&D (built around hitting things) necessarily the best system for the Immortal game (not built around hitting things).
Thinking about it I definitely want to keep the 5 save approach (that or do I undertsand that 5th Ed uses a 6 save approach - one for each stat?)
However, one could go to ascending saves, but one would have to choose a base DC that is the standard target - probably 20. This has the advantage that it handles penalties to saves slightly better at high levels when the target number is 2 but there are both bonuses and penalties to apply.