further advancing celestial monster classes (3.5)

[Narylinn]

I'm totally new here, so please forgive my newbieness if I didn't search well enough and this has already been posted about.

While I'm not playing in any groups at the moment, I find some of the celestial races, specifically the astral deva and trumpet archon (from Savage Species) and the avoral guardinal (updated 3.5 version in the Planar Handbook) appealing as potential PC races. However, one thing I'm not really clear on is if these can be advanced beyond the monster classes as described not by taking regular or prestige class levels but simply by advancing them with their outsider type, and, if so, does it work as I'd think?

For example, let's take the avoral guardinal, which finishes its monster class progression at ECL 15 with 7d8 HD (giving it +7 BAB and +5 base saving throws), SR 25 (10 + class level), and caster level 8 for its spell-like abilities, plus some other abilities which presumably wouldn't increase further simply with more racial HD (+8 natural armor, DR 10/evil or silver, and others). What I'm talking about would be this: when the character gets to 120,000 XP and thus can advance to ECL 16, instead of taking a level in, say, ranger, instead take a level of outsider type, which would, if I'm assuming correctly, advance the character to 8d8 HD, +8 BAB, +6 base saving throws, SR 26, and caster level 9 for its spell-like abilities (as presumably natural armor bonus and DR wouldn't increase), plus get 8 + Intelligence modifier skill points? Then, upon reaching 136,000 XP for ECL 17, could this character take another such level, going to 9d8 HD (and thus +9 BAB), caster level 10 for spell-like abilities, and skill points as before, plus a feat for getting to 9HD? I realize this is may not be as favorable in terms of character advancement as taking levels of a regular character class or prestige class, though while this route would, if I'm speculating correctly, still offer a 1/1 BAB progression, the fastest save progression on all saving throws, increased spell resistance, eventually getting to Large size (at 15HD, as per the MM), and an increase in caster level for spell-like abilities (up to a limit of 20th, which seems to be the maximum caster level for monster spell-like abilities), while advancing with another class wouldn't increase SR or CL for spell-like abilities.

I'd think it would be a similar story for the astral deva, though it might be more complicated for the trumpet archon, which gets a spellcasting progression as part of its monster class levels; when the trumpet archon finishes its progression at ECL 20, it has 12HD and casts spells as a 14th-level cleric (as the monster class says, HD + 2, which is kind of bonkers early on since an ECL 2 trumpet archon gets cleric spellcasting ability and thus casts spells as a 4th-level cleric). If the trumpet archon were to take my hypothetical outsider class level when it gets to ECL 21, would its cleric spellcasting ability increase to 15th level as part of that, or is that the end of it in terms of spellcasting advancement as part of a monster type progression, and levels of cleric or some prestige class that advances divine spellcasting be required for further caster level and spell progression? The Fist of Raziel PrC (from the Book of Exalted Deeds) looks like it would work well with a trumpet archon wanting to advance beyond ECL 20, since it has the fastest BAB progression and gets spellcasting progression at every level but first, so presumably an ECL 22 astral deva Fist of Raziel 2 would have a BAB of +14 and cast spells as a 15th-level cleric.

[Esprit15]

RAW, the class ends.

Personally, I would be fine with advancing abilities after that.

[Narylinn]

RAW, the class ends.

What I should have mentioned in the original post was that there's a paragraph in Savage Species that implies, at least in my interpretation of it, that a PC monster can continue advancing by type beyond the end of its monster class progression. In Chapter 3: Monster Classes, there's a section about creating an eight-level minotaur monster class, since the minotaur is a 6HD creature with a +2 LA. The paragraph starting near the end of page 27 says:

"After reaching 8th level, the minotaur can continue to advance using the monster advancement rules in the Monster Manual, if desired. Monstrous humanoids have a great base attack progression (equal to a fighter's) and two good saves, so there is good incentive to advance this way. Other good options for continuing to develop a minotaur character include advancing as a fighter (for the bonus feats), a barbarian (for rage and certain skills), or a rogue (for sneak attacks and even more skills)."

The implication I take from this is that it must be meant for a PC who goes through this class; if it's for a minotaur the DM creates as a foe or NPC for the PCs, talking about advancing the character beyond 8th level by monster type (monstrous humanoid, in this case) would seem superfluous, as the DM should already know about advancing a monster by type from the Monster Manual, and the XP possesed by and (E)CL of foes and most NPCs (excluding cohorts and such) doesn't matter. However, what I don't quite get about this, if I'm interpreting correctly, is that there's no adjustment based on which type of monster is being advanced; thus, outsiders get the best of almost everything at every level: 1/1 BAB progression, good progression on all saves, 8 + Int modifier skill points, and a d8 hit die, plus, in many cases, spell resistance and improved caster level for spell-like abilities. For comparison, though, giants get much less for advancing by type: 3/4 BAB progression, good Fortitude and poor Reflex and Will save progressions, only 2 + Int modifier skill points, and the same d8 hit die. Thus, while taking levels in a regular or prestige class might be better than advancing as an outsider, a giant has little incentive to advance as a giant, given the option, as s/he'd be spending the same number of experience points for fewer benefits. I could be completely wrong in my interpretation of that paragraph, though, and maybe it is just reminding the DM of options for an NPC progression. I wish they'd have released errata for Savage Species, but apparently they never did.

[Hackulator]

The answer is you can do whatever the hell you want/your DM allows, but there are not specific rules for it as far as I know. There are rules for advancing monsters by HD but not a direct conversion to levels that would give you xp values.

Please not the fact that you can do whatever the hell you want as long as your DM allows it stands for all questions.