Infernal Wave is the hardest hitting realiable ability you have as a AOE sorc. If you spec into Lengthening Shadows you can hit it from almost 90 yards. You dont have do be close at all to use it.
Don't ever think that you'll be spamming Shattered Shadows as your bread and butter. Its situational at best (Example: Hitting people around oil on keeps). Put up Ice spikes, Infernal wave on cd, set up pit of shades, rinse and repeat. You can grab shadow knives if you want but its really not that great. Disastrous Cascade is also very very very situational, if you need a short range aoe its better to just use Surging Pain since you can move while you use it. Black Horror is alright, but others classes can debuff INI more reliably, so it's a personal preference.
Grab lengthening shadows and neverending agony from Destruction tree to reduce the CD and increase range of Infernal Wave. With the remaining points I usually take Gloom of Night for a AOE dot and Hand of Ruin to finish priority targets or people running away. (both from Calamity tree)
This is what I run at 60+:
https://builder.returnofreckoning.com/c ... 29,5427&t=
The maxed out Destruction is simply to buff the damage of the abilities.