Spell Enhancer and casting times

[Biggus]

Spell Enhancer (SC) says it enhances "the next spell you cast this round". Does that mean you have to finish the spell this round, or can it apply to spells with longer casting times as long as you start to cast them this round?

More generally, do other spells and effects which enhance casting (eg Mystic Surge (PHB2)) only work if you finish the spell in the allotted timeframe, or do you only have to start them?

[Zanos]

The description for casting time says that you spend a full-round action casting the spell in every round until the casting is completed. So I think it should work fine on spells with longer casting times, since it doesn't specify that you have to complete the casting before the end of the round.

[Biggus]

Thanks, Zanos.

As it appears from the lack of response there's no RAW on this, let me rephrase the question: would you allow Spell Enhancer and similar effects to work on long casting time spells if you were DMing?

[Zanos]

What I posted is RAW. You cast the spell in the same round, you just didn't complete the casting. The action that you take in every round leading up to the completion of a casting is casting.

As far as opinion goes, I don't see why not?

[Biggus]

What I posted is RAW. You cast the spell in the same round, you just didn't complete the casting.

Where is it specified that "cast" means "start casting"?