Fastblood Aspect reduces CD per Blood Orb pickup. 3 waves = ~20 Orbs, each Orb reduces by 3 seconds or so.
There’s other ways to reduce Ultimate CDs, too - but Fastblood is the easiest with a large CD amount.
There’s also two new Unique Pants
One is for Shadow/Blood that has an affix to massively reduce Wave CD. I think with GA and Masterwork, you can cap to 75% pretty easily.
The other is for Bone/Blood that gives a flat -2 second per Bone Spear, and produces many Spears. I haven’t had them drop yet, but my understanding is that one or two casts is enough to refresh it.