Question: I played a D&D 3.5 campaign years ago, and one PC was a druid. The player did a pretty awesome job as a spy thanks to the multiple divination spells, Wild Shape and especially A Thousand Faces:

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> [**A Thousand Faces (Su)**](http://www.d20srd.org/srd/classes/druid.htm#aThousandFaces)  
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>  At 13th level, a druid gains the ability to change her appearance at will, as if using the [*disguise self*](http://www.d20srd.org/srd/spells/disguiseSelf.htm) spell, but only while in her normal form. This affects the druid’s body but not her possessions. It is not an illusory effect, but a minor physical alteration of the druid’s appearance, within the limits described for the spell.
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I'm now planning to run a Pathfinder campaign (albeit with a custom world) with a lot of druids and I just don't understand how Thousand Faces fits for a "protector of the wild, lover of Nature" kind of guy (and I've never seen this ability used since this spy-druid), so I'm considering dropping A Thousand Faces.

Did you ever read something justifying this ability, in D&D or Pathfinder material or anywhere else, even real stories on druids?

**EDIT :** What bugs me is that I can't see proper use of this ability besides deception, and deception doesn't feel too "natural".

Answer: 
I have not heard of a historical/fictional druid that had a particular ability to change their face.

However, this seems like a fairly straightforward extension of the 3.5 Druid's earlier abilities - namely Wild Shape. A 13th-level Druid is an accomplished shapeshifter, they are used to changing their form and flesh into those other than their own.

This could even be tied to a 13th-level Druid suddenly having the realization that humanoids are not so different from animals at all.

I can imagine that the idea for the ability surfaced when someone asked the question: "Wait, my high-level Druid can change their face to resemble that of any kind of animal, but not to look like the face of another human?"
I think you are looking at the ability wrong. Think about nature. There are a ton of animals which use deception as a means of defense or to hunt.

Victoria Butterflies mimic Monarch Butterflies because one tastes bad. Stick insects pretend to be sticks to keep away predators. Angler fish dangle little pseudo minnows in front of their face to attract prey. 

If you stop thinking of A Thousand Faces as "Deception" and start thinking of it as "Camouflage" you might find the ability to be more helpful.