If you looking for general build: https://overframe.gg/build/262143/

This build is specific for hemocyte plague star killer. Because of dmg cap per pellet, weapon with high innate multishot like [Pyrana Prime] is perfect for killing it. Other alternative: [Tenet Detron], [Kuva Brakk], [Kuva Hek] alt fire, also shotgun in general as they have good multishot too (shotgun use corrosive because of primed charged shell).

This build require fully stripped armor from hemocyte ,use shattering impact Vastilok or sarpa (only vastilok/sarpa/[Stropha] work with SI because their bullet have impact, [Redeemer] bullet are 100% blast hence not working, [Stropha] is slow) [Seeking Shuriken] or whatever to full strip armor

it also work on Lephantis derelict boss at phase 2 (when 3 head with 1 big body), for phase 1 (three seperate head) use highest dmg weapon possible since there's no dmg cap such as sniper or exodia contagion throw or [Glaive]

Using blast as element because blast give only 50% bonus dmg compare to corrosive which deal 75% as image below, but corrosive cannot utilize [Primed Heated Charge], so blast still deal more dmg to it. (1.5 x 255% blast > 1.75 x 180% corrosive). If you still don't have [Primed Heated Charge], just use regular corrosive as substitute.