Base attack bonus of a character who acquires outsider levels

Question

I'm attempting to represent a character who is a 12th level Wizard / 4th level fighter who then acquires 15 HD of outsider levels. Which base attack bonus is correct?

12th level Wizard / 4th level fighter (16 HD total) provides a +10 base attack bonus.

Base attack bonus can then progress in one of two ways adding an outsider's base attack bonus equal to total Hit Dice equivalent to a fighter:

1. +15 base attack bonus addition. Making a full attack at this base attack bonus is equal to +25 +20 +15 +10

   or

2. 17 HD to 20 HD provides a +4 addition to base attack bonus, this is accounting for 4 HD of the 15 HD outsider's hit dice. Making a full attack at this base attack bonus is equal +14 +9 +4 then following the rules for epic progression accounting for the remaining 11 HD of the 15 HD outsider's hit dice providing +6 epic attack bonus. Which in total results in making a full attack at base attack bonus + epic attack bonus of +20 +15 +10.

Normally, I wouldn't ask such a basic question. However, I note the Solar Angel is a 22 HD creature and its base attack bonus is +22; if it was following epic level progression, its base attack bonus should be +21.

Answer 1

Not exactly clear.

This would generally place it in the purview of your particular DM.

Hey I Can Chan already mentioned how even the rules are contradictory.

If we go by process of elimination and disregard contradictions, we can take this rule:

Epic characters—those whose character level is 21st or higher—are handled slightly differently from nonepic characters. While epic characters continue to receive most of the benefits of gaining levels, some benefits are replaced by alternative gains.

and conclude that the intention is to create a deliberate departure from the fairly obeyed notion of symmetric rules for PC and NPCs in this edition. Which disqualifies #1.

I do however want offer a third alternative, on the basis of one or both the following points:

1. Generally in matters of order or precedence, the game defaults to the most favourable interpretation for the player.

2. Type is what you are and class is training and life experience. The natural ordering seems to be racial hit dice first, then class.

So, a result I'd consider equally viable, if not the most logical, would be 15 Outsider HD, then the class progression. Meaning a minimum of 17 BAB (15 outsider + 5 wizard) or a max of 19 BAB (15 outsider + 4 fighter + 1 wizard). The rest of the levels end up as part of the epic attack bonus.