I created a tainted sorceress npc as a friend of one PC. Shes a human sorcerer 4/tainted sorcerer 2 specializing in crowd control and nonlethal damage spells. She is neutral, but because of taint her alignment might change to evil. I am afraid that PC paladin might want to kill her. I wonder what prestige classes with full spellcasting progression could improve her survivability or provide a way to avoid getting oneshoted.
I think you are asking the wrong question here. First of all, spellcasters focused on crowd control are usually one of the strongest type of spellcasters if not the strongest type of spellcasters.
What do you want to know, probably, are what spells make a spellcaster less killable at low level. A brief list is:
- Fly/Spider Climb: (fighters, paladins, rangers, barbarians, etc etc) can't fly without potions, objects, or extremely specific builds. You fly or walk on the ceiling? They can't attack you if they are melee focused characters.
- Invisibility: As fly...except there is no potions since see invisibility is a personal spell...so there is even less possibilities they can harm you.
- Distorsion: 50% miss chance on every attack against you.
- Darkness, Fog cloud, etc etc: Everything that create concealment can cause the attacker to miss as per the distorsion spell.
- Many other.
My question, anyway, is: why a paladin want to kill a neutral friendly character?
A paladin is not a killing machine. If he think the sorcerer is going on the path of evil...well...he need to help her to stay neutral. Not kill her. A paladin does not kill every being that results evil to his detect evil. A paladin kill only when he need to kill if we are talking of humanoid type of characters. If we are talking of undeads, ofcourse, is another story.