Improved Familiar, Celestial, and HD

[Tinalles]

Improved Familiar lets you get a Celestial (or Fiendish) version of any of the ordinary base familiars.

But is that template applied based on the familiar's one hit die, or based on the master's 3+ hit dice?

The familiar rules say "Hit Dice: For the purpose of effects related to number of Hit Dice, use the master's character level or the familiar's normal HD total, whichever is higher." The Celestial template has different effects depending on the base creature's HD. So, by RAW, then, a celestial familiar's abilities would continue to increase as the caster gains levels.

By RAI, I think it's assumed that you're calculating that based on just the familiar's one base hit die. Otherwise your celestial weasel would get a ton of spell-like abilities over time.

[Are]

The Celestial template isn't the Half-Celestial template. See the Monster Advancement page for the Celestial and Fiendish templates.

As you can see, the only thing that changes with number of HD is the DR and resistances. If you allow the master's HD to count for the template, these bonuses won't break anything.

However, in my opinion, the template is applied directly to the creature. It's not an effect, so the master's HD wouldn't come into play.

[Tinalles]

Ooooh, I've been looking at the wrong template. Imagine a fail trombone going "wah wah wah" in the background.

Looking over the ACTUAL Celestial template, it wouldn't even matter much if you used the Master's HD, since all it does at higher levels is make the creature harder to kill. Handy for a vulnerable little familiar, but purely defensive.

[Benchak the Nightstalker]

Tinalles wrote:

Ooooh, I've been looking at the wrong template. Imagine a fail trombone going "wah wah wah" in the background.

Looking over the ACTUAL Celestial template, it wouldn't even matter much if you used the Master's HD, since all it does at higher levels is make the creature harder to kill. Handy for a vulnerable little familiar, but purely defensive.

Don't forget the Celestial familiar's ability to Smite Evil 1/day. Adding HD to damage could give that weasel a pretty nasty bite, provided you use the Master's HD.

[Mistwalker]

Are wrote:

However, in my opinion, the template is applied directly to the creature. It's not an effect, so the master's HD wouldn't come into play.

I would disagree.

"Hit Dice: For the purpose of effects related to number of Hit Dice, use the master's character level or the familiar's normal HD total, whichever is higher."

As the amout of DR and the resistances change with the number of Hit Dice, to me, this indicates that the familiar would get the increased DR and resistances.

In my opinion, RAW and RAI intend for the familiar to get a little harder to kill at higher levels.

[Talon Stormwarden]

Also consider that the other options for Improved Familiar are things like quasits, imps, and pseudodragons. Celestial is pretty subpar if you don't use the master's level for hit dice. I think RAW and RAI are that the master's level be used.