Adjusting dragon's CR -- no spellcasting, possibly no SR

[Klaus]

So I don't like my dragons casting spells. And I think SR is kind of a bummer for PCs.

How do I adjust down the CRs if I remove both abilities? What if I remove only spellcasting?

 

[Jhaelen]

Use the Xorvintaal template from MM5: It does exactly what you want:
You're exchanging SR & spellcasting for one or more cool abilities while the CR remains the same.

 

[RangerWickett]

So I don't like my dragons casting spells. And I think SR is kind of a bummer for PCs.

How do I adjust down the CRs if I remove both abilities? What if I remove only spellcasting?

Actually, the guideline is that a new special ability is +1 or +1/2 CR point, so drop the CR by 1 or 2. Lower age category dragons will miss the powers less, but great wyrms will lament the loss of mage armor and shield and haste and the ability to give the middle finger to spellcasters.

 

[Quartz]

Essentially, you're creating a half-dragon dinosaur so use the CR for that.

 

[Zurai]

The SR won't be much of an issue to any party that should reasonably be fighting the dragon (ie, level-appropriate encounter). SR is at most CR + 6, so even if the dragon is a +4 CR encounter, that's still a greater than 50% chance to land any spell. At that point, either Assay Spell Resistance or the Arcane Mastery feat will allow the casters to pretty much ignore the dragon's spell resistance.

Losing spellcasting is a much bigger deal.

 

[Thurbane]

Use the Xorvintaal template from MM5: It does exactly what you want:
You're exchanging SR & spellcasting for one or more cool abilities while the CR remains the same.

I second this as the best option.

 

[Klaus]

Use the Xorvintaal template from MM5: It does exactly what you want:
You're exchanging SR & spellcasting for one or more cool abilities while the CR remains the same.

Very interesting! I'll have to check this out.

 

[blargney the second]

The Xorvintaal stuff is pretty nifty, and worth checking out. You can even just ignore the Great Game stuff to make them scrappy dragons.

Option 2: grab some of the metabreath spells from Draconomicon. They have two advantages - 1) they help the dragon beat the crap out of adventurers and cause the PCs grief with its breath weapon; and 2) they're swift actions so it still gets to act appropriately dragony (you can even make it look like it's not casting spells at all).

You could change the SR by bumping it up a couple of points, then make it block only half of the spell effect if they fail to penetrate. This will make it even less likely to succumb to anti-climactic save or hosed effects, but more vulnerable to direct damage spells.
-blarg