Those who are so assured of Disjunction should beware the following (thrown together in 2 seconds, with no thought to Spellcraft DCs).
Disjoin the Dsjoiner
Abjuration
Level: Epic Spell
Components: V, S, M, XP
Casting Time: 1 day
Range: personal
Duration: 1 year
Saving Throw: Yes (see text)
Spell Resistance: No
When the caster of this spell finds himself in the area of effect of a Mordenkainen's Disjunction, two things occur.
1) The Disjunction rebounds upon the original caster. Its area of effect is now centered on the caster's location. All other effects (including saving throw DCs) are as normal for the original caster.
2) After the disjunction rebounds, the original caster is struck by a blast of negative energy and gains Xd4 negative levels. A Fortitude save DC X reduces the number of negative levels gained by half.
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The X's are because I didn't want to try to figur out the spellcraft DC for this spell. However, you could completely drop clause 2) and probably have a fairly low DC spell. Especially if you make it a ritual with as many casters sacrificing whatever slots they can spare.
Disjunction will certainly rule the day for the side it works for, assuming they can immediately follow it up with a winning blow. Otherwise, the other should be able to escape to regroup.
And of course, you have to kill the dragon in one blow, because he is a Red Dragon Sorcerer, meaning he has access to Heal as one of his spells known.
