Changes to Alter Self, Polymorph, Polymorph any Object, and Shapechange in regards to Monster Race Classes:
Alter Self
Transmutation
Level: Brd 2, Sor/Wiz 2
Components: V, S, F
Casting Time: 1 standard action
Range: Personal
Target: You
Duration: 10 min./level (D)
You change your form into a similar one to your own. If you are a humanoid, you may change into a different humanoid. If you are a magical beast, you may change into a different magical beast. If you are a quadruped, you may only change into other quadrupeds and so on and so forth. You lose all class levels and racial bonuses/abilities and gain a number of class levels of the new form equal to your HD - 2 or CL - 2, whichever is lower (maximum 5 HD, minimum 1 HD). You retain your own hit points, alignment, ability scores, skills, feats, and equipment (if the new form is capable of holding it; it melds into your new form otherwise). You gain the creature's saves, BAB, type (and subtype, if applicable), movement modes and class abilities. If the new form does not have enough levels to cover the difference (ie, Wizard 5 to Drow 1), you do not gain any other monster levels but you do get the benefits of having up to your limit in HD (you would gain Web Path abilities up to 5 HD if you are a Wizard 7, meaning Deadly Aim for the Assassin Web Path, but not Defense Pierce, which is a 10 HD ability and beyond the scope of the 5 HD cap, even if you are a higher level Wizard). If the creature would gain ability score bonuses, add those to your character at the appropriate levels/HD. You lose your race's ability score changes due to temporarily losing your race.
You also lose access to your spellcasting ability, as the Tenser's Transformation spell. The only exception to this is if the resulting creature has spellcasting ability, you regain access to your own spells up to the maximum level of spells that creature could cast. Again, a Wizard 7 turning into a Drow 1 and taking the Dark Mage Web Path would gain access up to 3rd level spells but not beyond; the 5 HD cap is still present. This applies even if the spellcasting is of a different variety (such as Divine spells or Psionic manifestations whille being an Arcane caster).
Changing back from the new creature to your original form is a move action that does not provoke attacks of opportunity. Doing so ends the spell. Just as the original spell, you may delegate minor attributes of the physical form such as skin and hair color, physique, or even scars or tattoos. These must fall within the norms for the creature in question. If you utilize this spell to create a disguise, you gain a +10 circumstance bonus on your disguise check.
You may not utilize this spell to gain access to Prestige Monster Race Class levels (any creature marked with a prerequisite is considered a Prestige Monster Race Class level) nor any templates. It is highly recommended that you have a stat block crafted and readied before utilizing this spell for the DM's sanity and your own. The DM may rule that without a stat block already drafted, the spell fails.
Focus: A clay model of the type (Animal, Magical Beast, etc.) and subtype (Good, Evil, Fire, etc.) of the form to be turned into, mixed with diamond dust worth at least (HD^2 * 50) GP. You may add more clay and diamond dust to increase the amount of HD available but are still limited as per the spell.
Polymorph
Transmutation
Level: Sor/Wiz 4
Components: V, S, F
Casting Time: 1 standard action
Range: Touch
Target: Willing living creature touched
Duration: 1 min./level (D)
Saving Throw: None
Spell Resistance: No
This spell functions as Alter Self with the following exceptions: Your HD limit raises to 10 and you may change into forms that are different from your own (except for gaseous or incorporeal creatures). You are still relegated to CL - 2 or HD - 2, whichever is lower. This spell is only usable on willing targets. You still may not assume prestige levels nor templates, even if your CL or HD exceed the new creature's.
Focus: A clay model of the type (Animal, Magical Beast, etc.) and subtype (Good, Evil, Fire, etc.) of the form to be turned into, mixed with diamond dust worth at least (HD^2 * 50) GP. You may add more clay and diamond dust to increase the amount of HD available but are still limited as per the spell.
Polymorph Any Object
Transmutation
Level: Sor/Wiz 8, Trickery 8
Components: V, S, F
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One creature, or one nonmagical object of up to 100 cu. ft./level
Duration: See text
Saving Throw: Fortitude negates (object); see text
Spell Resistance: Yes (object)
This spell functions as normal but can also be used to assume the form of a race class. The target gains class levels equal to CL -2 or HD - 2, whichever is lower (maximum 15 HD). It otherwise functions as Polymorph, with the duration based upon the difference chart. Creating a creature out of stone or any other material does not automatically put it under your control, nor is it automatically friendly to you. Treat it as a newly summoned NPC without a master that will act according to its alignment and/or natural instincts.
Casting this spell a second time causes the first effect to end and the spell to be determined as if you are your normal race and class.
Focus: A clay model of the type (Animal, Magical Beast, etc.) and subtype (Good, Evil, Fire, etc.) of the form to be turned into, mixed with diamond dust worth at least (HD^2 * 50) GP. You may add more clay and diamond dust to increase the amount of HD available but are still limited as per the spell.
Shapechange
Transmutation
Level: Animal 9, Drd 9, Sor/Wiz 9
Components: V, S, F
Casting Time: 1 standard action
Range: Personal
Target: You
Duration: 10 min./level (D)
This spell functions as Polymorph with the following exceptions: You may now assume gaseous and incorporeal forms and, as a swift action, you may shift between any number of forms as often as you like over the duration of the spell. Also, your limit is now equal to your CL - 2 or HD - 2, whichever is less (there is no maximum HD). Also, excess HD can now be covered with prestige classes and/or templates.
Focus: A clay model of the type (Animal, Magical Beast, etc.) and subtype (Good, Evil, Fire, etc.) of the form to be turned into, mixed with diamond dust worth at least (HD^2 * 50) GP. You may add more clay and diamond dust to increase the amount of HD available but are still limited as per the spell. For each race class changed into, you must have an appropriate model.
For all intents and purposes, HD is calculated as character level minus LA and is not affected by any ability that raises or lowers a character's hit dice or level, such as a bard's music or enervation-type effects.
Please, PLEASE review this and critique it before linking to it. I think I've covered most of the bases but may have forgotten a few key details. Yes, I did leave out the whole Ex abilities, Sp abilities, and Su abilities from the normal restrictions on the spell. I believe that when you're trading casting power for raw physical power or other-ability power, you're giving away a lot for some more situational benefits.
[Edit]Put in a small tweak to Shapechange that I'd forgotten. Namely the prestige classes and templates.[/Edit]
[Edit2]Changed limits to HD/CL - 2 for more power but still balanced.[/Edit2]
[Edit3]Clarified that HD adjustments from sources other than class levels do not affect how strong a creature you can become.[/Edit3]
[Edit4]Modified Alter Self to specify that regaining spells is based on YOUR OWN SPELLS.[/Edit4]
[Edit5]Added a focus with a cost to all spells, though this may change.[/Edit5]
[Edit6]Modified focus descriptions.[/Edit6]