Variety of rules questions

[Cybertron2]

Hey guys, just need to ask some general questions for my campaign in the forgotten realms

1) What happens to a deity when they're controlling their avatar (e.g. like in Out of The Abyss)
2) What exactly is the connection between the divine planes and the material plane (e.g. why don't the demons/devils just send 20 pit fiends down to conquer a large part of the forgotten realms considering the vast size of their armies) or why doesn't a god permanently have an avatar on the material plane wrecking up the place so as to gain more followers.
3) When Karsus killed a god and the new god was reborn changing the rules of magic (can't remember their names), did this affect all the planes/worlds or just the forgotten realms? Additionally was this change retroactive so theoretically if a villain went back in time could they cast the 'old' magic (such as the 10th level spells).

Many Thanks

[SharkForce]

1) generally speaking, not much. the avatar is a semi-independent entity most of the time, sent to do the deity's bidding. there are occasional exceptions (the time of troubles, for example), but mostly a deity does not *need* to pay attention to an avatar. that's the whole point of an avatar.

2) depends on the setting partially. in the forgotten realms, Ao will take away your divinity if you try to do certain things as a deity. for the devils, i expect they're mostly busy fighting the demons (and vice versa), and they're all busy fighting against various celestial beings.

3) just the forgotten realms and the surrounding space. if this was second edition, i could tell you that each setting has a crystal sphere surrounding it's "space" (as in outer space, but in 2e it was called wildspace, and you're more or less talking about the "solar system" out as far as double the distance to the furthest planet in the system) beyond which setting-specific laws cannot pass (and leads to an area where extraplanar beings cannot reach). this isn't second edition, but since nothing has been updated in spelljammer (and no, i don't include 4e stealing the name to have things that are definitely NOT spelljamming ships in anything but name) you'll need to decide why. in any event, the weave itself does not extend into the planes, with the probable exception of the parts that are home to various FR deities.

edit: missed the last part of your third question. the answer: all the old powerful magic still happened and was not retroactively taken away, so if you somehow travel to that time period you should be able to use that magic while in that time period.

[Sigreid]

3) just the forgotten realms and the surrounding space. if this was second edition, i could tell you that each setting has a crystal sphere surrounding it's "space" (as in outer space, but in 2e it was called wildspace, and you're more or less talking about the "solar system" out as far as double the distance to the furthest planet in the system) beyond which setting-specific laws cannot pass (and leads to an area where extraplanar beings cannot reach). this isn't second edition, but since nothing has been updated in spelljammer (and no, i don't include 4e stealing the name to have things that are definitely NOT spelljamming ships in anything but name) you'll need to decide why. in any event, the weave itself does not extend into the planes, with the probable exception of the parts that are home to various FR deities.

If I remember right, and I might not, the sphere around a world obeyed whatever the world's rules were. Wildspace referred to the space between the spheres where it was near impossible to predict with any certainty what the rules might be. At least that's what I think I remember.

[Goober4473]

I'll also add that if you're the DM, these answers are pretty much up to you.

Also, I'm running Out of the Abyss right now, and I don't recall any avatars appearing anywhere in it. The demons lords are actually in the Underdark for real, not aspects avatars or proxies, and they aren't gods in any event.