What is the most damaging one shot spell?

[Uber Dungeon]

I am interested to know What everyone thinks is the most Damaging on shot spell of any level without metamagic, Such as kelgore's fire bolt or shocking grasp.
Caster Level of the spell would be level 20 wizard.

All published 3.0, 3.5 and Pathfinder materiel is acceptable reference.

 

[Altamont Ravenard]

Disintegrate is 40d6, so an average of 140 pts of damage.
Weird can instantly kill a great number of creatures.
Wail of the Banshee can potentially deliver 200 points of damage to a maximum of 20 targets, so 4000 pts of damage in one spell.
Transmute Blood to Acid does 40d6 points of damage over 4 rounds, and attackers suffer 3d6 pts of acid damage per strike. If you surround the Medium target with 8 level-20 fighters making full attacks against the afflicted creature, that's another 8 X 4 X 3 = 96d6 of damage, for a total of 136d6 of damage, or an average of 476, still far below the potential of a Wail of the Banshee.

AR

 

[Argyle King]

Are you trying to deal the most damage or look for a spell that's the most deadly? Some of the most lethal spells are ones which don't deal damage at all.

 

[RUMBLETiGER]

Minor Creation.
To make Black Lotus Extract (scroll down) because it is a "nonmagical object of nonliving plant matter".
Since a Vial holds 1 ounce of liquid, and Minor Creation makes 1 cubic foot per level, and there are about 957 Ounces in a cubic Foot, you're looking at 3d6 x 957 Constitution damage x level of the caster.
Constitution damage is based of Hit dice, not hit points, so a much smaller number to drop to 0 in order to kill.
That's 957 fortitude saves DC 20 to make in an instant or drown in life-sucking death. Since it's a Wizard spell level 4, usable as a Wizard level 7, you're looking at 3d6 x 6699 Constitution damage, which is somewhere between 20,097 and 120,582 points of Constitution damage.
Use the Psionic Version to deal between 2871 and 5742 Constitution damage at level 1.

Expect your DM to hit you with something if you try this.

 

[Empirate]

Maze.
No save, gone for some rounds, just mop up the rest of the opposition, then gang up on the mazed target.

Good with Chain Spell, it must be said.

 

[aglondier]

Minor Creation.
To make Black Lotus Extract (scroll down) because it is a "nonmagical object of nonliving plant matter".

-snip-

Expect your DM to hit you with something if you try this.

So...how much xp is the population of Waterdeep/Greyhawk worth?

 

[Rich Baker]

While Disintegrate is a ton of raw damage, I think Destruction (the 7th level cleric reverse of Resurrection) stands up pretty well. Unlike Disintegrate, you don't need to make a ranged touch attack, so there's one small "miss chance" removed. You're guaranteed 10d6 damage even on a successful save, and of course you kill the target outright on a failed save. But, more than that, you kill the target *hard* -- his buddies will need to use a 9th level True Resurrection to bring him back, whereas you can use the dust from disintegrate is OK for a 7th-level Resurrection. So if how thoroughly you kill the target counts, Destruction is pretty, well, destructive.

 

[Jester David]

Disintegrate.

Just pair it with Improved Critical (ray) and jack the save DC as high as possible. 80d6.

 

[Empirate]

Potentially, Avasculate tops all other damaging spells. Just depends on how many HP the enemy had in the first place...

Oh, and on a similar note, if you can get a 3.0 Harm houseruled in, you're golden! Unless the opposition also has that spell...

 

[radja]

instead of black lotus extract, I'd create one of the inhaled poisons. Although the damage per target is lower, a single dose of inhaled poison affects a 10ft cube, allowing you to hit more targets per dose (depending on size of the victims). This magnifies the possible damage on medium creatures by 4, and allows an area of slightly more than 300 x 300 ft to be covered in a 10ft high poison mist.