When is the number of storm copies checked?

[Tobi]

I play 7 spells followed by Tendrils, then my opponent casts Stifle, targeting the storm trigger, I have Force of Will and counter his Stifle.
With how many copies does the storm trigger resolve now?
Is the number of copies checked
1. at the time I play the spell having the storm trigger (meaning 7 copies in this example), or
2. is it checked when the storm trigger resolves (which would be 9 copies here).

My tip is: 1 

[Toad]

Answer is written on the card

Storm (When you play this spell, copy it for each spell played before it[/B] this turn. You may choose new targets for the copies.)

Since Stifle and FOW were cast *after* the Tendrils of Agony, they won't up the Storm count.

[Dante]

Answer is written on the card

Storm (When you play this spell, copy it for each spell played before it[/B] this turn. You may choose new targets for the copies.)

Since Stifle and FOW were cast *after* the Tendrils of Agony, they won't up the Storm count.

Yes, listen to Toad you should, hmmmm. 

A more technical explanation is that Storm trigger goes on the stack when you play the spell.  So the stack would look like this (resolving from top down)

storm trigger (x=7, number of spells played before the card with storm)
Tendrils

if the opponent doesn't respond with stifle (or their stifle is countered), the storm trigger resolves and you place the copies on the stack, so it would be:

copy of tendrils
copy of tendrils
copy of tendrils
copy of tendrils
copy of tendrils
copy of tendrils
copy of tendrils
actual Tendrils


also, remember that storm counts ALL spells played before the Tendrils, so if you cast 7 spells and the opponent cast 1-2 (brainstorm, counter, etc), those all count towards the storm count too.  Countering your own spells is a valid way to up storm count if you need to.