How can I go out with a bang?

[MrWoodchip]

Or, preferably, a THWOOOOOM with a field of corpses left behind. I'm not talking something that can be re-used, since I don't want to break the game, but a oneshot item (or combination of items) or effect that will kill anything near me, and probably me too.

Relevant information:
I have 20 UMD, 15 Knowledge(The Planes), 12 Bluff and 19 Diplo, 20 hide and 15 move silently, and my class levels are Rogue 6/Fighter 2/Planar Ranger 1/Hellbreaker 3, for 12 total. I'll be taking 2 more rogue, and 1 more Hellbreaker levels until 15, then warlock for 3 levels, for reasons, then hellbreaker forever (Will likely be going to epic levels, and the steal spell-like/supernatural ability is great at high levels). The GM is fast and loose with valuable loot, though we have to fight hard for it. I am chaotic neutral. The campaign is in hell and generally combat is against evil outsiders.

What I have so far is:

• Pazuzu. Can only use him once, since it'll make me chaotic evil, and he doesn't help that alignment.
  
  
• Staff of power/the magi with retributive strike. A maximum of 50*8 damage (based on how many charges it has) with a DC17 reflex for half. 50/50 chance of killing me or transporting me to another plane (which will kill me for story reasons).
  
  
• Filling my type 4 bag of holding with acid, holy water (in hell), acidic fire, alchemist fire, and whatever else, then dumping it out on the square I want to destroy (and killing me with the splash damage).
  
  
• Doing a Gandalf. Very circumstantial. (Hint: "Fly, you fools!")

[frogglesmash]

Craft contingency "Locate City Bomb" that goes off when you die? Are you even allowed to add metamagics to contingencies?

[Curmudgeon]

There's a fairly straightforward way to accomplish this.

• Get an NPC Druid to cast Mantle of the Fiery Spirit (Sandstorm, page 118). For 16,200 gp (6,200 materials & services; 2,000 XP @ 5 gp/XP) you'll Instantaneously be granted the fire subtype.
• Take the Final Strike feat (Savage Species, page 34). As a fire subtype creature you'll go up with a blast of light when your HP reach -10 or lower.

[Red Fel]

Pity you can't retrain your class levels. Jade Phoenix Mage (Tome of Battle) was made for this. Its capstone lets you detonate, burning everything within 20 feet for half-fire, half-untyped damage and banishing targets to their native planes. (Not necessarily useful if you're the extraplanar one, but still, big baddaboom.) Oh, and you respawn shortly thereafter, fully healed, which makes it a great ability when you're about to die and surrounded by hostile uglies.

It is a once-a-week ability, but you weren't concerned about reuse, anyway.

[MrWoodchip]

Both of those are perfect. I'll likely do the detonation one with some future character.

[(Un)Inspired]

There's a fairly straightforward way to accomplish this.

• Get an NPC Druid to cast Mantle of the Fiery Spirit (Sandstorm, page 118). For 16,200 gp (6,200 materials & services; 2,000 XP @ 5 gp/XP) you'll Instantaneously be granted the fire subtype.
• Take the Final Strike feat (Savage Species, page 34). As a fire subtype creature you'll go up with a blast of light when your HP reach -10 or lower.

Final Strike has always been one of my favorite feats.

[illyahr]

For small scale, drop a portable hole into a type 4 bag of holding, or vice versa, and watch things implode as you tear a hole in the multiverse.

For large scale, hold-the-multiverse-hostage type damge, drop a sphere of annihilation into a well of many worlds and unmake every point in the multiverse at once.

[Flickerdart]

If you have a high Intelligence, you would deal a lot of damage as an intellect bomb.

[Telonius]

EDIT: Didn't see the alignment above .... ah well. Last minute change of heart, perhaps?

The Exalted Fury spell from Book of Exalted Deeds. Level 9 Sanctified spell. Everything evil within 40 feet of you takes damage equal to your current HP plus 50, but you die.

[Sagetim]

There's some other sanctified spells that result in you dying too, like the one that deals 2d6 per caster level as you explode in fire, then get ressurected a while later.

I would go for a bag of holding and portable hole, but only after jumping into a big bad's mouth so you do it on the way down to their stomach. No saving throw for them that way.

[Thealtruistorc]

I believe Apocalypse from the Sky exists in scroll form. Combine with metamagic spell completion and there is no boom to rival it (well, save for Jade Phoenix Mage invisible body outside body chaining).

[Jormengand]

You could find some kind of magic item that allows you to cast Vengeful Gaze of God. For when you absolutely, positively gotta kill a guy.

[Socratov]

Well, there is always asking the party wizard to write lots of notes with widened explosive runes, covering yourself in them, and then reading only one to trigger everything. (or just cast off your cloak and hug the nearest baddie)

[Curmudgeon]

Well, there is always asking the party wizard to write lots of notes with widened explosive runes, covering yourself in them, and then reading only one to trigger everything.

What makes you think that would happen? As near as I can tell you'll trigger the one you read, and its explosion will guarantee the destruction of the bits of parchment all the others are written on.

[Socratov]

What makes you think that would happen? As near as I can tell you'll trigger the one you read, and its explosion will guarantee the destruction of the bits of parchment all the others are written on.

I was under the impression that destroying the parchment the explosive rune is written on also triggers the spell.

[Curmudgeon]

I was under the impression that destroying the parchment the explosive rune is written on also triggers the spell.

Nope. Only attempting to Dispel or Erase the Runes will trigger the spell. Destroying the parchment just destroys the parchment (and the Runes get ripped to pieces and aren't runes any more).

[marphod]

There's a 9th level Wu Jen spell that makes you awesome for a while, and then Kills You Dead, Dead, Dead, Do Not Pass Go, Do Not Collect 200$ Dollars, No Save.

Ah, Transcend Mortality, Complete Mage. DR 30/Epic (should have been 30/-), ER all/50, SR 21+CL, Lots of immunities, +10 Enhancement to all Saving Throws. 1 Round/Level, cast-able as an immediate.

(Although I did think it made it hard to be brought back, but a simple Res or True Res is sufficient according to the spell text.)