I have a party with a level 10 druid, and she was told she can transform into any elemental.
When the party was injured after a particularly tough encounter, she transformed into Positive Energy Elemental and started making non-lethal touch attacks to the party members, effectively healing them 1d6 health per action (She transformed into a medium elemental, since I wasn't sure, I just made it 1 size smaller for non-core elementals).
Given that this effectively translates to 5 full party heals a day, I am hesitant about whether this is a legal course of action. I know I allowed it once, so I should probably stick with it, but for future campaigns, is this legal?
Assuming I disallow changing into 3rd-Party creatures, which this elemental is, is it advisable that I allow Wild Shaping into non-core elementals, like Ice and Lightning?
Best Answer
Officially, the druid can't use wild shape to assume such a form...
The druid supernatural ability wild shape allows the druid to use an effect duplicating the spell elemental body I at druid level 6, II at level 8, III at level 10, and IV at level 12.
The spell elemental body has no provision for elementals other than air, earth, fire, and water. Of the elementals listed on the d20 Pathfinder SRD that I looked at (cold iron, gravity, lightning, time, and, to make sure, positive energy), none address nor alter the spell elemental body.
If the GM allows the druid to take such nonstandard forms and gain such nonstandard abilities, these are house rules, and the GM should make it clear to all players that they are house rules and explain how they work.
Expanding the druid's wild shape abilities in this way is something Pathfinder deliberately shut down in an effort to make druids less powerful, druids having been among the most powerful classes in Pathfinder's antecedent, Dungeons and Dragons 3.5.
...But house rules can make it happen anyway
First, the GM should look at the elemental body spells and provide details as to what effects assuming the elemental body of an nontraditional elemental has. Then the GM can create for the campaign a custom feat, magic item, or spell that allows assuming nontraditional elemental bodies. (However, unless the abilities granted by the nontraditional elementals are vastly superior to the traditional, once the details are hashed out, it's perfectly reasonable for mere familiarity (as suggested by GnoveltyGnome's now deleted answer) to be sufficient for assuming those forms.)