For the build you're playing (looks like Jaetch melee build) unity is the best choice indeed.
Also you're missing focus and restraint combo that amps dmg by a lot so the poster above is completly wrong - it may be hard to pass grift 40 +- dps check in your current gear.
Few things to note:
1. Diamon in your helm gives you close to zero benefits - your only cd skill is teleport and it's cd is supposed to be reseted with dmg through illusionist, since you're taking dmg anyway to proc Halo or Arlyse.
2. Parthan defeners have no crit roll and that's a major dps loss.
3. Esoteric alteration is better then gizzard for this build since it allow you to facetank nasty ground effects much better.
4. Electocute dmg on belt is irrelevant since it servers 2 purposes: stacking dynamo and procing Tal. Dmg comes from meteors and hydras, not from electrocute.
So replacing gem in helm and rerolling belt will add you some durability, Then it's the matter of double unity, better serpent sparker and parthan defenders. Build is pretty consistend and fun, but don't exept to facetank 50+ rifts becouse ppls who do so have extremly good gear,