Our T29 2pc and 4pc set bonuses are fairly boring but strong. There is no need to pay attention to them to maximize the benefit.
Our T30 2pc and 4pc set bonuses effectively turn our Sundering into a big burst damage window akin to Colossus Smash or Essence Break. Using the buffed Chain Lightnings is worth it even in single target.
Look for any items with Haste and Mastery to upgrade with your Crests.
For your embellishments, you want to run the set consisting of Wind Spirit's Lasso and Scale Rein Grips.
For your trinkets you want to run two out of Neltharion's Call to Dominance, Ominous Chromatic Essence (attuned to Haste or Mastery) and Harlan's Loaded Dice. Dragonfire Bomb Dispenser is very good on single target, but not a good general purpose trinket like the other ones.
The effect on Seal of Diurna's Chosen is extremely strong and more than makes up for having our not preferred stats, even compared to a lot of Season 2 rings.
Onyx Annulet is not worth using over Season 2 rings.