advice crafting +5 chaos staff

Hi intermediate player here and trying out the bane occultist build for the first time. I'm trying to make the plus +5 chaos staff. I started with a damage over time fractured base and harvest crafted the +3 to all chaos skill gems. I'm looking for the next step to get the +2 to socketed gems, is my best bet to "prefixes cannot be changed and then harvest craft "caster mods?" Thanks. In game name is "Prize_kart"

Magister has incredibly low weight. If you are making a +5 staff, you will never hit it the way you detailed. I hate to say it but harvesting +3 was a wasted step. Your best bet to making this staff is fossil crafting (Aetheric - Corroded - Metallic - Shuddering) to get +5. Craft of Exile says 1 in 43 tries at 63.644% confidence.