Tessarael said:
Following up on what hong said, I had a quick look through the SRD to see which 9th level spells I consider broken or plot device spells:
Mage's (Mordenkainen's) Disjunction: removes spell buffs and destroys magic items, broken because the first side to disjunction the other will usually win. This spell has been nerfed for arena smackdowns.
Miracle, Wish: plot device for undoing something bad
Shapechange: in my opinion it's way too good a buff spell. Change into a different dragon each round to use a different breath weapon each round, etc.
Time Stop: time out to buff et al., probably not broken as allowed in arena smackdowns.
Those are the only 9th level spells that look really disturbing to me. There are lower level plot device spells and spell combinations that may also be an issue (Find the Path, Scry + buff + Teleport, etc.), but should have already been dealt with by this stage.
Bah. Those spells are only "broken" when used in a campaign with a DM who either 1) is unprepaired for the level of play he has chosen or 2) is just running the same style of scenario he's been using since 1st level.
I'm running a campaign that has reached the beginnings of epic level, and I've not found any 9th level spells that were "broken". The mage has all of the spells you mentioned - and more. I take his abilities (and those of the other players, like the fighter who can reliably dish out 200 points of damage a round) into account when I design my scenarios.
Here's some things about those spells you might not have considered:
1) Disjunction. Sure, the PCs can totally hose the bad guy. One spell, and all the magic items he's got are gone. But then, what's left for the PCs after the battle? My PCs will almost
never Disjoin a bad guy - they want his stuff after he's dead.
2) Miracle, Wish. Both take 5000 XP - nothing to sneeze at. Miracle requires total alignment with the deity - and that may not always be the case. Wish either gives some pre-configured benifits (inherent bonuses and whatnot) or risks dangerous results. DMs shouldn't wimp out when the PCs ask for more that the usual stuff.
3) Shapechange. Notice that the HD cap for the creature you change into is your caster level or 25 HD, whichever is less. If your 20th level party is fighting an Old Red Dragon (CR 20) then it would be fairly irrelevent for the mage to shapechange into say, a Young Adult Silver Dragon (CR 13, 19 HD). Sure, he'd get some extra HPs and a 10d8 cone of cold, and perhaps a better BAB - but he coulda just cast a Comet Swarm (a Meteor Swarm with cold damage). That's a 9th level spell too, and it does 32d6 of unsaveable damage. Which would you do? You'll quickly find that HD 20 monsters aren't that much more effective at fighting CR 20 monsters than the mage was to begin with.
4) Time Stop. This is the only spell that must be carefully watched - but as long as the DM keeps a close eye on it, it's fine. The DM must
strictly enforce the "unable to effect other creatures" clause in the spell. That really eliminates it's offensive use. At that point, it's just a "get a few personal buffs off" spell, and that's not that bad. Or, if you are the mage in my game, it's used for replacing alcoholic beverages with water - without alerting your host. (See, he's got this Vow of Abstenance...)
Those 9th level spells may look all big and bad, but as long as the DM is aware of the abilities of his players, and plans accordingly, the opposing monsters can be equally nasty. My players just recently had to fight their way out of an ambush set by a CR 21 blue dragon and a CR 22 green dragon - when the PCs had no idea dragons were around. Given that the party consists of two 20th level characters and two 21st level characters, it was a tough battle, and it used every spell the mage and cleric had over 6th level (and the mage had 3 10th level slots!). They were victorious, and it was an amazing fight - but never an easy one.