Vermin with Fiendish Creature Template

[Shin Okada]

Usually, a template does not add skills nor feats as a creature with template still retains the features of the original type, and the number of HDs does not change.

But in case when a fiendish creature template is added to a vermin, the creature's INT score changes from "-" to 3. Should this change give skills and feats to a fiendish vermin?

And, in my understanding, now a fiendish vermin is not mindless and loses the immunity to all mind-affecting effects, right?

 

[Ranes]

Vermin with the template become magical beasts, so I think the answer to both of your questions is 'yes'.

 

[Rabulias]

As an official example, The Sinister Spire adventure includes fiendish monstrous spiders. They are labeled as "magical beast (augmented vermin, extraplanar)" and have an Int of 3, and retain their immunity to mind-affecting effects.

 

[nijineko]

Also, this trick works for the celestial template too.

Do note that a creature thusly affected can now take class levels.

 

[Cleon]

Usually, a template does not add skills nor feats as a creature with template still retains the features of the original type, and the number of HDs does not change.

But in case when a fiendish creature template is added to a vermin, the creature's INT score changes from "-" to 3. Should this change give skills and feats to a fiendish vermin?

And, in my understanding, now a fiendish vermin is not mindless and loses the immunity to all mind-affecting effects, right?

Sorry, but I think the official interpretation is Fiendish Vermin don't gain skill points or feats unless the original creature had them.

Firstly, the few examples of Fiendish Vermin I've seen in published sourcebooks (i.e. the Fiendish Spider Swarm in the aforementioned Sinister Spire) didn't have skill points or feats.

Secondly, the template says "A fiendish creature uses all the base creature’s statistics and abilities except as noted here" and it doesn't have a skills or feats noted anywhere. Furthermore, it says you don't recalculate the skill points for the change in type (to Magical Beast in this case).

A literal reading suggests it retains the mindless trait too, despite it no longer having an Intelligence score, since the template says it retains all the special qualities of the base creature.

Personally I don't like the notion so if I was running the game I'd have Fiendish Vermin gain skills and feats and lose the Mindless trait, but be aware that's probably not following the template.