Major Spoiler ahead!! Do not read unless you have completed the game, or want to be spoiled! You have been warned!
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OK, I've defeated Irenicus at the Tree of Life and appeared in Hell. Now, all the walkthroughs and posts I've read indicate that the player would NOT be able to rest or save the game in this location. But I've experimented, and found I could do both! Could anyone comment on this?
FWIW, I have both the SoA and ToB official patches installed, and no unofficial ones.

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"Butt-kicking for goodness!" - Minsc
"Cities always teem with evil and decay. Let's give it a good shake and SEE WHAT FALLS OUT!!" - Minsc
http://www.dabros.net/images/tcampbell/hadb6copy.jpg

not sure what you read but you can rest as much as you like in that area.

I was able to rest and/or save before ToB or any patches as well.

IF you had used summons during the fight with Jon Irenicus at the Tree of Life, you will not be able to rest in Hell because, surprise! Surprise! The game still thinks you are engaged in battle with J.Irenicus and you will see battletext between your summon and J.Irenicus who will not fight back.

And of course, this means you cannot rest because the game thinks you're still engaged in battle.

As a result, I never used summons again to fight J.Irenicus at the Tree of Life.

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If not a Sorcerer, then a Paladin.
http://www.gifs.net/animate/dflysb2.gif
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Baldur's Gate Item Mart

Hmmm...that's pretty interesting. I've never heard that before. Well, I was able to rest and save at will while in Hell, but I guess that's because I don't summon monsters for Irenicus.

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a bunch of long hairs.
trux

the reason summoned monsters won't allow you to save is they get teleported with you to hell and keep fighting jon. however, eventually they will get unsummoned and everything is fine.