Anti Disintegration Tactics
Having recently created a high level spellcaster, I have recently been confronted with the spectre of Fort-Save-Or-Die magic effects as well. While so-called "death effects" weren't too hard to manage through some snappy PrC work, the Disintegrate spell gave me some headaches. Given that my character will be sporting a DC 35 Disintegrate, I decided right away that I needed to have the tools at hand to survive my own attacks, reasoning that we'd likely be up against enemies at LEAST as powerful.
Here's a short list of what I found applicable. Your mileage may vary. Note that I'll be listing every countermeasure I can think of here, including a few the original poster wished to exclude. This isn't aimed specifically at the original poster's issue...it's more of a general thing. With one hand do I give, with the other do I smite.
1) Spellward: Disintegrate. A magic weapon can be given this +1 effect from Magic of Faerun. Spellward allows the weapon to absorb any one spell (with no noted restrictions save that it can't be area effect) harmlessly, then re-release it on a following turn as a standard action. This is the solution I wound up using in creating the Guardian Sceptre item I tote around.
2) Save boosts. This can, in theory, work better. The idea is to use a combination of arcane and divine buffs to whack your Fort save WAY up there. Endurance (or items that raise Con), Protection from Spells (or items that give resistance bonuses) and morale bonuses (via Emotion or similar) are all in the purview of the arcane. Divine casters then get a bevvy of other options. Problem here is that it requires time to set up. You may not have that time.
3) Misdirection/Evasion tactics. Be where the green ray is not. Invisibility or Displacement is good. 50% miss chance. Mirror Image is grand as well. These depend on the foe being suceptible to illusions and so on though. A single True Sight can ruin your day. Similarly, crank that touch AC falls into this category. Mages have a surprisingly large amount of spells that help with this. Shield gives a cool +7 to touch AC for a mere 1st level spell. Haste adds another +4. If you use any of Mr.Cook's spells, the Warding Globe spell allows up to +6 in deflection bonuses. Ghostform from Tome and Blood can be useful, especially for sorcerors, since it causes the caster to become incorporeal. Not only do you get that flat 50% miss chance (which does apply to Disintegrate, since it uses an attack roll and is not a force effect) but you also get a deflection bonus equal to your Charisma modifier.
4) Counterspells. This is mainly applicable if the meanie has an extra partial action...which if he's 23rd level, he most certainly should for any serious fight. Save that partial and watch the wizard like a hawk. Feats relating to counterspelling (improved counterspell and reactive counterspell) can be of immense aid here.
5) Other keen items. The Ring of Spell Battle from Magic of Faerun allows an automatic counterspell action, and can thus be quite handy. Granted it's only 1/day, and only a Dispel Magic counter, so there's still a caster level check. The Ring of Nine Lives allows autosuccesses on saves (up to nine, but usually less).
6) Epic Stuff! If the critter is caster level 23, are you following the Epic Level Book? An Epic Spell using the Ward seed could easily (and rather cheaply, comparatively speaking) block all spells of 6th level or lower...kind of like a "Globe of Absolute Invulnerability" or something.
Also, some possible clarification on item use. Not saying anyone's wrong; just putting some more evidence on the table.
Note that in Tome & Blood, in the part talking about familiars, we see that animals (and by extension, magical beasts) can be said to have item "slots." Some animals may not have the full range, but since magic items, by default, scale themselves to their owners, an animal that is either trained to tolerate it...or smart enough to put up with it...can wear most magic items that aren't specifically designed for humanoid features (a la gloves).
This suggests to me that a dragon, which has "fingers" that are capable of manipulating the environment, could probably wear rings. It might have trouble with cloaks, due to the wings. Boots too probably wouldn't work so well. Not that items that fulfill similar roles couldn't be custom made by or for dragons.
Having recently created a high level spellcaster, I have recently been confronted with the spectre of Fort-Save-Or-Die magic effects as well. While so-called "death effects" weren't too hard to manage through some snappy PrC work, the Disintegrate spell gave me some headaches. Given that my character will be sporting a DC 35 Disintegrate, I decided right away that I needed to have the tools at hand to survive my own attacks, reasoning that we'd likely be up against enemies at LEAST as powerful.
Here's a short list of what I found applicable. Your mileage may vary. Note that I'll be listing every countermeasure I can think of here, including a few the original poster wished to exclude. This isn't aimed specifically at the original poster's issue...it's more of a general thing. With one hand do I give, with the other do I smite.

1) Spellward: Disintegrate. A magic weapon can be given this +1 effect from Magic of Faerun. Spellward allows the weapon to absorb any one spell (with no noted restrictions save that it can't be area effect) harmlessly, then re-release it on a following turn as a standard action. This is the solution I wound up using in creating the Guardian Sceptre item I tote around.
2) Save boosts. This can, in theory, work better. The idea is to use a combination of arcane and divine buffs to whack your Fort save WAY up there. Endurance (or items that raise Con), Protection from Spells (or items that give resistance bonuses) and morale bonuses (via Emotion or similar) are all in the purview of the arcane. Divine casters then get a bevvy of other options. Problem here is that it requires time to set up. You may not have that time.
3) Misdirection/Evasion tactics. Be where the green ray is not. Invisibility or Displacement is good. 50% miss chance. Mirror Image is grand as well. These depend on the foe being suceptible to illusions and so on though. A single True Sight can ruin your day. Similarly, crank that touch AC falls into this category. Mages have a surprisingly large amount of spells that help with this. Shield gives a cool +7 to touch AC for a mere 1st level spell. Haste adds another +4. If you use any of Mr.Cook's spells, the Warding Globe spell allows up to +6 in deflection bonuses. Ghostform from Tome and Blood can be useful, especially for sorcerors, since it causes the caster to become incorporeal. Not only do you get that flat 50% miss chance (which does apply to Disintegrate, since it uses an attack roll and is not a force effect) but you also get a deflection bonus equal to your Charisma modifier.
4) Counterspells. This is mainly applicable if the meanie has an extra partial action...which if he's 23rd level, he most certainly should for any serious fight. Save that partial and watch the wizard like a hawk. Feats relating to counterspelling (improved counterspell and reactive counterspell) can be of immense aid here.
5) Other keen items. The Ring of Spell Battle from Magic of Faerun allows an automatic counterspell action, and can thus be quite handy. Granted it's only 1/day, and only a Dispel Magic counter, so there's still a caster level check. The Ring of Nine Lives allows autosuccesses on saves (up to nine, but usually less).
6) Epic Stuff! If the critter is caster level 23, are you following the Epic Level Book? An Epic Spell using the Ward seed could easily (and rather cheaply, comparatively speaking) block all spells of 6th level or lower...kind of like a "Globe of Absolute Invulnerability" or something.
Also, some possible clarification on item use. Not saying anyone's wrong; just putting some more evidence on the table.
Note that in Tome & Blood, in the part talking about familiars, we see that animals (and by extension, magical beasts) can be said to have item "slots." Some animals may not have the full range, but since magic items, by default, scale themselves to their owners, an animal that is either trained to tolerate it...or smart enough to put up with it...can wear most magic items that aren't specifically designed for humanoid features (a la gloves).
This suggests to me that a dragon, which has "fingers" that are capable of manipulating the environment, could probably wear rings. It might have trouble with cloaks, due to the wings. Boots too probably wouldn't work so well. Not that items that fulfill similar roles couldn't be custom made by or for dragons.
