Spell Compendium - Stunning Breath, am I reading this right?

[Bill Bisco: Eloquent Elf]

The Spell Compendium Spell Stunning Breath, gives your breath weapon the quality that creatures taking damage must make an additional fort save or become stunned.  But note that the spell has a duration of Instantaneous?! 

Do you cast this spell once, and you gain its benefits forever by RAW?

[Tr011]

Creatures that take damage from the breath weapon must make successful Fortitude saves (DC equal to your breath weapon save DC) or be stunned for 1 round.

Don't see how this could possibly be forever. Even if no duration would be noted, you would just stun, and the effect would immediatly go away (since it's instant not permanent)

[veekie]

I think he means the breath weapon becomes permanently enhanced that way.

[Talore]

Would it not just last indefinitely, then expire as soon as you use your breath weapon once?

[Esgath]

True Strike (PHB), Divine Retribution (CC) and Footsteps of the Divine (CC) all state, that the effect of the spell ends, when you use it that way. Stunning Breath doesn't and there would have to be a clause for instantaneous spells stating, that their effect can't last longer than a certain time, that it wouldn't last forever.
Yeah, that could mean every Dragonfire Adept or whatnot with a breath weapon could grab himself a ring of spellstoring (normal or major) or similar means and get Stunning breath (, Greater) permanently on his breath. Then sell the item afterwards. Or just borrow it

[skydragonknight]

That's a typo. The original spells had a breath weapon component and all had a casting time of 1 standard action and a duration of instantaneous (except animate breath, which had a duration iun rounds for obvious reasons). All the revised versions have a casting time of 1 swift action and a duration of 1 round, except for Stunning Breath. All the casting times were changed correctly but an unfortunate oversight left Stunning Breath at Instantaneous, which means:

Instantaneous

The spell energy comes and goes the instant the spell is cast, though the consequences might be long-lasting.

Compared to Permanent:

Permanent

The energy remains as long as the effect does. This means the spell is vulnerable to dispel magic.

So basically by RAW, your breath is stunning while the spell is being resolved, but loses that property once the spell effect has been resolved, since the spell energy is gone. And since the use of a breath weapon is no longer part of the same action as casting the spell, the Spell Compendium version does absolutely nothing when cast by purest RAW.

But it's an obvious typo - given the way all the other instantaneous breath spells were revised the true duration is obviously supposed to be 1 round and would be house-ruled as such for the sake of consistency alone in any reasonable game.

[awaken DM golem]

Psionic Lion's Charge ... has the same problem.

Don't ; but that's obvious.

[Esgath]

So basically by RAW, your breath is stunning while the spell is being resolved, but loses that property once the spell effect has been resolved, since the spell energy is gone. And since the use of a breath weapon is no longer part of the same action as casting the spell, the Spell Compendium version does absolutely nothing when cast by purest RAW.

But it's an obvious typo - given the way all the other instantaneous breath spells were revised the true duration is obviously supposed to be 1 round and would be house-ruled as such for the sake of consistency alone in any reasonable game.

Sure its a typo. But

Instantaneous

The spell energy comes and goes the instant the spell is cast, though the consequences might be long-lasting.

One could argue, that the consequence of the spell is, your breath weapon being permanently enhanced. Then it would be RAW.
Just mark it as TO and leave it at that.