Hello, I have a doubt about what is better between torrent of flame and flaming curse, for build liv 20. I see that at my level (12) torrent is very op, and all sister take it. At level 20 if consider clear sky, you should still take instead of curse?

So, nobody can help me?

If you're asking what to choose between torrent and curse, then I prefer curse now (a bit more cheap and instant, though demands killing cursed enemies and can be dispeled). Torrent may do more damage, but any more-or-less good tank blocks it with magic shield.
But I didn't get it about level 20.

I would disagree, Torrent is an excellent spell which is very good for taking out groups of enemies and gunnar outposts, curse is expensive and not guarranteed to do anything. I have both and use torrent multiple times every game and never use curse.

i agree with moosegun...very useful at taking out heavily fortified gunners