As best I can tell, it would work just like polymorphing any other time, so depending on what you would turn into, you may get some bonus senses or abilities, etc.
Class levels you have should almost certainly stay the same (you don't lose them through other polymorph spells), but you also won't really be just gaining the base statistics of the form you turn into. With the question about base save bonus, I assume you mean such as those gained through a creature's racial hit dice? Polymorphed creatures don't gain anything like that.
Perhaps an idea of the situation in question could be useful here? I'll give an example of how I think this should work though.
Level 15 Human Fighter is getting turned into, I dunno, let's say a Bugbear. This makes the Polymorph Any Object spell act like Alter Self. Darkvision and Scent from the bugbear overlap on abilities gained through Alter Self, so the Fighter now has those and also gets a +2 size bonus to strength as a medium humanoid.
The rest of his stats all stay the same though, and he still has 15 levels of Fighter, with all the class features that entails. He doesn't gain any of the stats of the bugbear aside from the new bonuses provided by the Polymorph spell (Darkvision, Scent, +2 size bonus on strength, as listed).
At least... I think that's how it works, as best I can tell? I really can't make any promises though. It's a little tough to say.
Also, I'm not sure if Human -> Bugbear would be a permanent alteration or not, but that was just for an example.
Darkwolf117 is pretty much correct. A GM may feel free to interpret this, however given that it's a duration of permanent instead of, say, instantaneous, it can be dispelled with a potent enough dispel magic check.
Also, as for which spell it imitates, I'd always opt for the highest for whatever you're doing (unless it's in the caster's best interest to choose a lower one), though that's just me.
Looking at the text of the spell...
This spell functions like greater polymorph, except that it changes one object or creature into another. You can use this spell to transform all manner of objects and creatures into new forms- you aren't limited to transforming a living creature into another living form. The duration of the spell depends on how radical a change is made from the original state to its transmuted state. The duration is determined by using the following guidelines.
<snipped the tables>
If the target of the spell does not have physical ability scores (Strength, Dexterity, or Constitution), this spell grants a base score of 10 to each missing ability score. If the target of the spell does not have mental ability scores (Intelligence, Wisdom, or Charisma), this spell grants a score of 5 to such scores. Damage taken by the new form can result in the injury or death of the polymorphed creature. In general, damage occurs when the new form is changed through physical force. A non-magical object cannot be made into a magic item with this spell. Magic items aren't affected by this spell.
This spell cannot create material of great intrinsic value, such as copper, silver, gems, silk, gold, platinum, mithral, or adamantine. It also cannot reproduce the special properties of cold iron in order to overcome the damage reduction of certain creatures.
This spell can also be used to duplicate the effects of baleful polymorph, greater polymorph, flesh to stone, stone to flesh, transmute mud to rock, transmute metal to wood, or transmute rock to mud.
That links us to greater polymorph (which links us to polymorph, and since they're both on the same page...)
This spell transforms a willing creature into an animal, humanoid or elemental of your choosing; the spell has no effect on unwilling creatures, nor can the creature being targeted by this spell influence the new form assumed (apart from conveying its wishes, if any, to you verbally).
If you use this spell to cause the target to take on the form of an animal or magical beast, the spell functions as beast shape II. If the form is that of an elemental, the spell functions as elemental body I. If the form is that of a humanoid, the spell functions as alter self. The subject may choose to resume its normal form as a full-round action; doing so ends the spell for that subject.
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This spell functions as polymorph except that it allows the creature to take on the form of a dragon or plant creature. If you use this spell to cause the target to take on the form of an animal or magical beast, it functions as beast shape IV. If the form is that of an elemental, the spell functions as elemental body III. If the form is that of a humanoid, the spell functions as alter self. If the form is that of a plant, the spell functions as plant shape II. If the form is that of a dragon, the spell functions as form of the dragon I. The subject may choose to resume its normal form as a full-round action; doing so ends the spell.
... which actually brings up some very interesting implications. Because, effectively, unless you use polymorph any object to affect the target by another spell (and possibly even then) the wording seems to imply that, regardless of the duration, the target can choose to resume its normal form as a full-round action (as per the polymorph and greater polymorph rules).
... this means that the baleful polymorph, flesh to stone, or other similar effects may, in fact, be useless, and a 'permanent' duration of the spell may not really be so permanent, if the recipient doesn't want it.
While this could have some very interesting RP consequences, I'm pretty sure that's not the intent of the spell ().
If you want to go with the intent, I'd suggest that the bottom line of the greater polymorph spell be dropped, and presume valid targets for transforming a creature or object come from the polymorph and greater polymorph list of creatures (and also a normalized list of non-rare mundane objects).
If you really wanted, you could choose to interpret the rules of permanent duration to be like reincarnate (which means you're stuck with it forever, basically), which many do, and, in fact, which is more to the original intent of the spell, as far as I can suss out (though the permanent duration making it able to be dispelled).
In the end, you don't lose your class levels or class traits (unless you're hit by a baleful polymorph or similar effect), though if you're forever transformed into a specific creature that has its own HD progression (like, say, a dragon), I'd rule that you'd be able to progress as that creature.
Remember, regardless of who the GM is, the ultimate interpretation of the rules is entirely up to them.
For example, in my own games, I tend to default to "more powerful, but wilder and less precisely controlled magic" (usually tending towards 3.X magical interpretations, but with more varied results), but PF has done a lot to nerf the power of casters, so your mileage may vary.
Hi,
The Polymorph Any Object spell can have a permanent duration. If it does, does does the character still get the base save bonus from their class, or is the entire save bonus replaced by the save bonus of the creature they turned into? Also, if a player gains enough levels in their form, do they still get the +1 bonus to any ability score? Any help would be very appreciated?
-HalfElfWizard
To reply to your questions more specifically (as my other post did tend to ramble and is somewhat obtuse towards your questions):
1) yes/no
In other words: they gain the bonus of their class, not the bestiary entry of the creature they turn into.
Check here for a concise list of what various monster types grant as you increase in HD. If you somehow end up with multiple "types", then, defaulting to the 3.X rules, you choose one as your "type" and the others as your "agumented <insert type name here>" subtypes, and basically gestalt the two types' benefits (choose the best attack bonus/saves/skills/etc). Note that none of the polymorph spells (to my current knowledge, and certainly none specified) specifically grant you the ability to turn into an outsider, fey, construct, ooze, or undead, so, unless the GM expressly allows it (which they'd have the right to do both by way of vague/contradictory wording in polymorph any object and by way of being GM), that could be read as being impossible with polymorph any object.
Whether or not you gain creature HD is heavily subject to GM interpretation, but most common readings would arrive at a "no" decision in PF's rules.
2) yes
In other words: becoming a new creature doesn't negate their normal progression - all creatures in PF run under the same rules, more or less, so at every four levels they gain +1 to an ability score of their choice, and feats at every odd level.