Good tactics and spells for fighting dragons?

[shau]

Obviously they have minions who cast most of the spells; and the spells not cast by minions come from scrolls the minions acquire. I mean, Duh!

I always thought this was the new style of dragon hoard. I mean, they can't lay around on piles of gold anymore, but they can hang out in a cave filled with traps that cost thousands of gp a piece, and that almost the same thing right?

[Zherog]

Exactly. And the best part is that those wacky PCs can't get fat on the dead dragon's loot!

[CalibronXXX]

Since you aren't at the level where you can cast minor creation the dragons you'll be fighting (hopefully) won't be Young Adults or older, meaning a ray of enfeeblement, especially when empowered, will beat the hell out of the bugger's melee damage; and will basically always take effect since the dragons won't have SR yet and the spell has no save.

So to re-cap a bit. Breath weapons are not scary, laughable casting abilities, Melee damage hosed by ray of enfeeblement, and can be taken out of the air by a Net or a Web spell.

It looks like dragons don't get terribly scary until higher levels to me.

[User3]

Dragons are dangerous spellcasting gishes. Practiced Spellcaster gives them better CL.

Consider a dragon with Rapid Metamagic, Quicken Spell:
Quicken Truestrike + Power Attack + Arcane Strike.
Even if Wraithstrike is banned, that is one badly mauled character.
If Wraithstrike is allowed seriously consider taking the Elusive Target feat with all frontliners.

High CR dragons have access to many epic feats. Epic Will and Epic Fortitude, added to their already high saves, can ruin an spellcaster day. Spellcaster Harrier may also be a problem, although some kind magical concealment should be there already.
Direct damage spells are suboptimal, but if the dragon is making all the saves having a few orbs memorized might help a lot.

Breath Weapons are often weak, but metabreath feats make them nasty. Quicken Breath allows for, you know, breathing as a free action. Lingering Breath turns the breath into a super Acid Arrow. Low level spells and some feats allow the dragon to alter the kind of breath they have. It is not nice when the Huge Red shots a cone of lightning on your fire-protected asses.
Not much to do, except maybe avoid giving the dragon tempting targets for the breath. Keep the party scattered and give rings of evasion to everyone that has a good chance to make the save.

Dragons can make weird feat choices too. And have PC class levels. You have seen nothing until you have seen a dragon with Exotic Weapon Proficiency: Spiked Chain, and a gargantuan-sized spiked chain...
Research your targets. Abuse Divination and Scry.

[Fwib]

Quickened True strike is a 5th level spell - unless the dragon has some 'ignore the metamagic costs' feat/ability which you do not mention, then (going by the SRD) that dragon is most likely CR19 or greater, so the PCs have at least 8th level spells, probably 9th - and the PCs are presumably competent in their use. In that case, 5th level spells doesn't sound like 'dangerous spellcasting' to me.

[edit] And a creature with 30HD with only 5th level spells doesn't sound like a good fighter/caster combination, either.