Victim said:
There are no countermeasures to MD. At least not any that don't cripple a character like always using your to counterspell just in case. The same divination spells that allow PCs to know who to avoid because they have MD also allow vile enemies to track down PCs and ruin their precious stuff. And having lots depth and personality isn't all that great if you can't do anything.
Disjuction would be broken even if it didn't knock out items. Say good bye to all the defenses needed to keep the uber-bad (or high level wizard) alive.
No countermeasures?
It's a close range interruptable spell...
Fight from further back, it's a close range spell, don't get in close range. or,
Cast anti-magic shell on the Barbarian and have him wade into the caster, the chance of blowing away the anti-magic shell is small and you better believe that the wizard will NOT like standing toe to toe with a Barbarian in an anti-magic shell. or,
Hit the caster with a maze, then surround the spot he was on, when he pops back in, waylay the crap out of him. Make sure at least two people surrounding him who are ONLY readying an action to disrupt casting, while the others pound on him. or,
Have your cleric load up on self-combat buffs, then wade in with his VERY nice Will Save to pound on the caster. or,
Have your own Arcane caster prepare MDJ and ready an action each round to counterspell MDJ. or,
Bust out the Diplomacy skill and convince him that casting something that nasty would be a bad idea, also discouraging disintegrate's and the like. or,
Ready an action to hide behind your Cube of Force, blocking Magic. MDJ is not in the list of items that affect the cube, I'd rule it doesn't work against it, cause it can't get through the screen the cube put up. (I would also rule that it drops the screen, but doesn't get beyond it). That's a gm call though. or,
Find out what he wants the most, dress up an item to look like it, claim you have it, then stick together. or,
Give the hasted monk an item of Silence 15' radius and have him dog the caster's every steps, not letting him cast anything but silenced spells.
Will each of these work? Probably not every time, but each of them (depending on your gm and how he plays certain things) has a chance of working.
There are reasonable countermeasures to every situation within reason.
Cedric