Not exactly, it is not a cone-type attack. As you see in the description, the sorcerer simply concentrates on a target area somewhere in his LoS, and the blast of energy appears immediately. It has a "ring" area (like Slow) with a 15' radius.
So it is centered on a specific target does that individual take damage?
I also hadn't considered the Stoneskin thing but it doesn't really bother me. So many
ToB foes are highly resistant to Fire damage that Dragon's Breath always had it's downside so it's only fair that Shockwave should too.
As I see it Shockwave would work by itself really well against the following kinds of targets.
1. Minions like in Yaga's army.
2. Litchs and foes who rely on Protection from Magic Weapons over Stoneskin.
3. Bosses who are resistant to fire & magic.
With a casting time of 1 Shockwave would also work well combined with other spells.
1. As part of an Aura Cleansing chain where Breach or some other similar spell came first.
2. Immediately after a Chain Contingency with Breach in it.
3. Immediately after another party member uses Breach, a load of Magic Missiles or some such.
All I have to say, again, is that Shockwave looks like a solid addition.