If you're that determined to destroy the place, use AftS and blast the entire planet into an asteroid belt
you forgot twinned.
also, the interesting thing about AftS is that it also summons atropus.
Well, with the coverage area on this particular one, I hope he can survive in space.
He's basically a moon-sized undead skull, so I'd say he can. Heck, all fights on Atropus (yes, that's on, not against) take playe undor no-atmosphere conditions in Elder Evils, because when he touches the surface it's alsready too late.
Omfg...what are his HD? Forget AftS, with my CL I can GATE IN UNICRON!
Atropus has no printed statistics.
The Aspect of Atropus that the party actually fights is described as "a small fraction of his will".
This has 66HD. So if your DM will let you control an Elder Evil that predates creation by virtue of your ability to Gate in a small fraction of his will, then by all means. (btw, per his statistics block Atropus isn't an outsider).
Incidentally, the moonlet itself presumably has conditions suitable for a living being to exist (I.E. air), and is considered a minor negative-dominant, low-gravity environment. so if you are controlling it you probably can use it to safely coast around the cosmos where you please.
On the off-chance the DM decides to invade your moonlet, make sure refer him to the encounter table in the same book:
(man tables with these forum commands suck, can't make em fancy or anything)
d% | Encounter | Average EL | Source |
| 1d3 famine spirits | 21 | MM2 96 |
| 1 advanced deathshrieker | 19 | MM3 32 |
| 1 corpse gatherer | 19 | MM2 51 |
| 1 ragewind | 19 | MM2 173 |
| 1d8 angels of decay | 19 | LM 83 |
| 1d2 nightcrawlers | 18 | MM 195 |
| 1d4 nightwalkers | 18 | MM 196 |
| 1d6 nightwings | 17 | MM 197 |
| 1d12 dread wraiths | 16 | MM 258 |
Atropus certainly gets more than his fair share of attention from that book.
I agree that his encounter is certainly the coolest setting, but honestly I'd be more afraid of seeing the Worm that Walks show up in a campaign.
His block lists him with Regeneration 10. The MM1 definition says that it will be noted in the creature's entry what effects deal regular damage to him. Since he has no such notations that means he doesn't take real damage from anything, which equates roughly to Tarrasque-levels of invulnerability. This not including his ability to discorporate and vanish in 1 round as an immediate action.