PoE Mageblood, Arcane builds without Original Sin

Back at work again today, can't play. Over the weekend I spent a good portion of my money upgrading my manabond character from the previous post. Got mageblood, 3rat talisman, rare boots and some other upgrades. Went from 12k es to 16k es, 8m to 18m dps. Not shabby but not where I want to be just yet. I still haven't purchased the forbidden jewels or squire. That's definitely the next step for me. My plans for the future include getting a gg ring, the kalandra's mirror ring, the squire, and the forbidden jewels, which all but taps out my budget, about 360 div

Path of Building question... as I scrolled past the "Precision" notable on the skill tree I noticed a huge bump in DPS which caught my eye. Was a bit surprised though because I am playing as a manabond hiero with cyclone + arc, so really spell based. I don't recall global accuracy being meaningful to spells. This notable plus the minor before give +10% cast speed as well but was skeptical that addition would result in \~13M+ additional damage. From what I can tell the trigger rate for manabond increases resulting in the higher dps. As a comparable test I added +10% cast speed on a dummy tes