Can you extend time stop?

Question

Time stop has a "duration" of 1d4+1 rounds, but it says it's apparent time and to see the text for further explaination. Knowing this, I wanted to understand wheter it's possible or not to extend time stop making it last 2d4+2 rounds.

Looking on the internet I have found people simply saying that i can be extended since it has a duration entry and it's not instantaneous, and people saying that the spell is essentially instantaneous even though it has a duration entry and can't be extended. If I wanted to use it as RAW as possible, what would be the correct way to interpret the spell?

Answer 1

I mean, you’ve pretty much laid out the options. There isn’t a lot more to say.

I’d comment that time stop is not instantaneous, even from the outside—technically it speeds up the caster an immense amount, but some finite amount of “real” time does pass. So if you double that time, and the time stop caster is still sped up just as much, they should have twice as much “apparent time” to work with.

And, for that matter, nothing in Extend Spell suggests that it only applies to “real” durations—it doubles the duration, whatever that is, or at least so long as whatever it is can be said to have a “length.”

So RAW, my feeling is that extended time stop—and worse, persistent time stop—is legal. That doesn’t mean the designers intended it, that you should allow it, or that you can expect anyone else to allow it. The RAW isn’t precisely air-tight, and in any event, RAW isn’t necessarily the same as intent or how things “should” be run.

As for what I would personally do, it’s kind of moot for me—I don’t run games that get anywhere near allowing 9th-level spells, and speaking hypothetically about games that do... does it even matter any more? You have 9th-level spells, and you can apply metamagic to them somehow—you’re already well past the point where 3.5e can have any claim to balance, or even stability. It’s a monstrous effort to even have a coherent campaign at those power levels, even with cooperative players.

Answer 2

Yes

By RAW it works, since the duration is given and is not ''concentration, instantaneous, or permanent'', apparent time is still time and it might look instantaneous for other creatures, but it's not for you. (the DM always decides anyways, see KRyan's answer for more details)

But pre-epic levels you can use arcane thesis (Time Stop) to do so since you only have 9th level spell slots and that Extended Time Stop would be a level 10 spell with the metamagic applied.

You need an additional feat for this to work or an item (and only metamagic of +1 or +0 can be applied with arcane thesis in this situation unless your DM accepts that +0 metamagic do reduce to -1 with arcane thesis (can't reduce spell bellow its original level)) I would allow it.

As @Hey I Can Chan reminded me: Sudden Extend can also be used to do so once per day. (As well as any other sudden metamagic feats) I still would allow it since it is only once per day.