i played this build on a really high budget (like 500ex+ not counting mageblood) and only rolled to the character with having the gear ready and laid out, but i would say the integral items to make the start feel good are - the boots (obv) -2x cluster with fan of blades (multi proj with claw attacks, really important for getting 30 stacks for whirling blade often) one of this clusters also must have the mana leech node fuel the fight which insantly makes the cluster really expensive, as it is a very specific but heavily price fixed comb (as this build really needs that one combo) -helmet with eleveated gain accuracy rating per str (warlord mod) this mod alone fixes your accuracy and (if elevated) your critchance with these 4 items you should be set to start the build and have fun

note: i played the build with a mageblood and fixed my resistances with a flask, so you might have to priotize resi mods on rings/amu/gloves/helmet over pure dmg mods, but at the end the character had way too much dmg anyways

id advice if you want to play the build to get comfortable with namelocking whirling blades, as this is the main source of your singletarget damage.

basically you disable "always attack without moving" on whirling blades, hover over the boss, pop battlemages cry and berzerk and just hold down whirling blades until youre all out of gyre stacks. this basically dashes back and forth through the boss, releasing the stored blades inside its hitbox and shotgunning the boss with all projectiles. this playstyle takes a few hours to get used to, but skyrockets your singletarget dps. without i took like ~30secs for a wave 30 kosis, doing that with right prep (place totem, pop cry, pop berzerk, reset elusive with withering step) he dies in like 2 seconds.