Hey, you may want to take a look at this spell, even though its 9th Level:
Fiery Body
School transmutation [fire]; Level sorcerer/wizard 9; Domain ash 9
CASTING
Casting Time 1 standard action
Components V
EFFECT
Range personal
Targets you
Duration 1 minute/level
DESCRIPTION
This spell transforms your body into living flame. You and your equipment are immune to fire damage. In fact, every time you would normally take damage from fire, you are instead healed of damage at a rate of 1 point per 3 points of damage the fire attack would have normally inflicted. You are immune to blindness, critical hits, ability score damage, deafness, disease, drowning, electricity, poison, stunning, and all spells that affect your physiology or respiration. You take only half damage from acid or electricity. You take 150% as much damage from cold than normal.
You gain a +6 enhancement bonus to your Dexterity score and a fly speed of 40 ft. (perfect maneuverability). Your unarmed attack deals an additional 3d6 points of fire damage, and you are considered armed when making unarmed attacks. Your body burns so brightly that creatures who do not avert their gaze from you are dazzled. Fire spells you cast have their save DCs increased by +1. If you enter water, you are surrounded by a 5-foot radius of steam and bubbles that grant you concealment (50% miss chance) but you take 2d6 points of damage each round you remain in water.
You might have a case because it says you are immune to anything that targets physiology. Being dehydrated, as Horrid Wilting does, affects physiology. If not, I would also suggest Undead Anatomy:
Undead Anatomy
School transmutation (polymorph); Level alchemist 3, magus 3, sorcerer/wizard 3
CASTING
Casting Time 1 standard action
Components V, S, M (a piece of the creature whose form you plan to assume)
EFFECT
Range personal
Target you
Duration 1 minute/level (D)
DESCRIPTION
When you cast this spell, you can assume the form of any Small or Medium corporeal creature of the undead type, which must be vaguely humanoid-shaped (like a ghoul, skeleton, or zombie). You gain a bite attack (1d6 for Medium forms, 1d4 for Small forms), two claw or slam attacks (1d6 for Medium forms, 1d4 for Small forms), and darkvision 60 feet. If the form you assume has any of the following abilities, you gain the listed ability: climb 30 feet, fly 30 feet (average maneuverability), swim 30 feet, low-light vision, and scent.
In this form, you detect as an undead creature (such as with detect undead, but not with magic that reveals your true form, such as true seeing) and are treated as undead for the purposes of channeled energy, cure spells, and inflict spells, but not for other effects that specifically target or react differently to undead (such as searing light).
Small undead: If the form you take is that of a Small undead, you gain a +2 size bonus to your Dexterity and a +1 natural armor bonus.
Medium undead: If the form you take is that of a Medium undead, you gain a +2 size bonus to your Strength and a +2 natural armor bonus.
Undead Anatomy II
School transmutation (polymorph); Level alchemist 5, magus 5, sorcerer/wizard 5
DESCRIPTION
This spell functions as undead anatomy I, except it also allows you to assume the form of a Tiny or Large corporeal creature of the undead type. If the form you assume has any of the following abilities, you gain the listed ability: climb 60 feet, fly 60 feet (good maneuverability), swim 60 feet, darkvision 60 feet, low-light vision, blood drain, DR 5/bludgeoning, scent, freeze, grab, mimicry, pounce, shadowless, sound mimicry, and trip.
In this form, you gain a +4 bonus on saves against mind-affecting effects, disease, poison, sleep, and stunning. If the form has a vulnerability to an attack (such as sunlight), you gain that vulnerability.
Tiny undead: If the form you take is that of a Tiny undead, you gain a +4 size bonus to your Dexterity, a –2 penalty to your Strength, and a +1 natural armor bonus.
Large undead: If the form you take is that of a Large undead, you gain a +4 size bonus to your Strength, a –2 penalty to your Dexterity, and a +4 natural armor bonus.
Undead Anatomy III
School transmutation (polymorph); Level alchemist 6, magus 6, sorcerer/wizard 6
DESCRIPTION
This spell functions as undead anatomy II, except it also allows you to assume the form of a Diminutive or Huge corporeal creature of the undead type. If the form you assume has any of the following abilities, you gain the listed ability: burrow 30 feet, climb 90 feet, fly 90 feet (good maneuverability), swim 90 feet, all-around vision, blindsense 30 feet, darkvision 60 feet, low-light vision, scent, constrict, disease, DR 5/—, fear aura, grab, jet, natural cunning, overwhelming, poison, pounce, rake, trample, trip, unnatural aura, and web.
If the creature has immunity or resistance to any energy types, you gain resistance 20 to those energy types. If the creature has vulnerability to an energy type, you gain that vulnerability. In this form, you gain a +8 bonus on saves against mind-affecting effects, disease, poison, sleep, and stunning. If the form has a vulnerability to an attack (such as sunlight), you gain that vulnerability.
Diminutive undead: If the form you take is that of a Diminutive undead, you gain a +6 size bonus to your Dexterity, a –4 penalty to your Strength, and a +1 natural armor bonus.
Huge undead: If the form you take is that of a Huge undead, you gain a +6 size bonus to your Strength, a –4 penalty to your Dexterity, and a +6 natural armor bonus.
Undead Anatomy IV
School transmutation (polymorph); Level sorcerer/wizard 8
EFFECT
Duration 1 minute/level (D) (see text)
DESCRIPTION
This spell functions as undead anatomy III, except it allows you to use more abilities. If the form you assume has any of the following abilities, you gain the listed ability: burrow 60 feet, climb 90 feet, fly 120 feet (good maneuverability), swim 120 feet, blindsense 60 feet, darkvision 90 feet, lifesense 60 feet, low-light vision, scent, tremorsense 60 feet, breath weapon, constrict, DR 10/magic and silver, DR 15/bludgeoning and magic, fast healing 5, fiery death, fire aura, grab, incorporeal, jet, poison, pounce, rake, rend, roar, spikes, trample, trip, and web.
If the creature’s form is incorporeal, the spell’s duration is in rounds per level instead of minutes per level, and your bite and claw (or slam) attacks are incorporeal touch attacks. If the creature has immunity or resistance to any energy types, you gain resistance 30 to those energy types. If the creature has vulnerability to an energy type, you gain that vulnerability. In this form, you gain a +8 bonus on saves against mind-affecting effects, disease, poison, sleep, and stunning. If the form has a vulnerability to an attack (such as sunlight), you gain that vulnerability.
Tiny undead: If the form you take is that of a Tiny undead, you gain a –2 penalty to your Strength, a +8 size bonus to your Dexterity, and a +3 natural armor bonus.
Large undead: If the form you take is that of a Large undead, you gain a +6 size bonus to your Strength, a –2 penalty on your Dexterity, a +2 size bonus to your Constitution, and a +6 natural armor bonus.
Or, you can turn your fighter and the grappling Monk into elementals, have them rush the lich and keep him busy. If someone's in his face, he won't be so concerned with casting spells.
