Specific overrides general, always; go with the ability.
- I had written an answer, it got lost in the æther -
In short, I'd rule the other way, I'd go with how Incorporeal(Ex) is written, under the assumption this is what the writer meant given that « At 15th level, you can become incorporeal for 1 round per sorcerer level. While in this form, you gain the incorporeal subtype. » are complete sentences, logically coherent on their own, needing no further explanation to be understood and they are the incipit of the ability text.
I think the writer tried to summarise the chunky bits of Incorporeal for the description of the bloodline ability and got lead astray by the sentence about Force effects.
This being said, I'd love the writers to sometimes discuss the intent behind wording, as part of the work itself. Here, a line saying « this is a departure from the Incorporeal monster trait » would have been useful if they meant the difference or « you gain the Incorporeal trait except for....». As it stands, I'd rule it wasn't an intended difference.
So, the sorcerer in the party just leveled up to 15 and gains this ability: https://www.d20pfsrd.com/classes/core-classes/sorcerer/bloodlines/bloodline s-from-paizo/undead-bloodline/
The page indicates that in the incorporeal form, he takes only half damage from physical sources if they're magical, including spells, but it says that non-damaging spells function normally. However, it says that they gain the incorporeal subtype and the subtype says that spells and effects that do not do damage have only a 50% chance of working.
So, how would you rule? Should I go with the 50% rule of the subtype, or the specific wording of the ability?
That's not what it says, or at least that is not how I parse this. It states:
Incorporeal Form (Sp): At 15th level, you can become incorporeal for 1 round per sorcerer level. While in this form, you gain the incorporeal subtype. You only take half damage from corporeal sources as long as they are magic (you take no damage from non-magic weapons and objects). Likewise, your spells deal only half damage to corporeal creatures. Spells and other effects that do not deal damage function normally. You can use this ability once per day.
In this form:
1. you gain the incorporeal subtype2. half damage from corporeal sources if they are magic
3. no damage from non-magic weapons and objects
4. spells that you cast deal half damage to corporeal creatures
5. spells that you cast that don't deal damage function normally
To me the last 2 sentences should be read together. This part of the ability is referring to spells that you are casting, not ones being cast on you. For that you have the subtype text which states:
Corporeal spells and effects that do not cause damage only have a 50% chance of affecting an incorporeal creature.