A lot of slow time for crowd control, teleport around and see meteor wrecking stuff, all you need for it to work are 8 set pieces and a RoRG, the rest are refinements, it doesn't need any specific weapon to work although an Aether Walker is essential for its full power.
For additional pieces you want:
Crown of the Primus for additional Slow Time power
Strongarm Bracers/Ancient Parthan Defenders for additional damage/survival
Nilfur's Boast for meteor damage
Focus+Restrait for obvious reasons but Convention of Elements+Unity/Halo of Alyse is a strong candidate.
For weapons you have tons of choices, Aether Walker, Serpent Sparkler, Thunderfury, whatever you got is good, also a cubed The Furnance is the best to have.
But none of the additional pieces are required for Delrasha so you can build it up very quickly and work from there without having to play on lower difficulties because you don't have the power. I started to work nicely in T7 and GR35 before I have any 6pc set because 4pc DMO and 4pc Tal alone are already powerful enough to wreck T6.