Bianca Ramba Achievement in Vampire Survivors

This is cumulative across all runs.

Milk Elementals are only found in the Dairy Plant, Stage 3. They are the white head/blob enemies that show up throughout the first ten minutes or so of the level. You'll likely need at least two or three runs of this level to get this many kills, since they don't show up in huge numbers throughout the entire stage. Just replay the stage as needed until this achievement unlocks at the end of your run.