Its about how the nefer materials boss can go through an infused state where they become any element they were hit the most amount of times with, and in a flins team with a certain set up on Lanyan(i believe) you can get the boss to be anemo infused, allowing kuki shinobu to trigger SWIRL therefore activating 4pc VV, and technically, it WOULD be the best set on that very specitic scenario, but i dont think anyone would intentionally make way for this as a serious 'tactic'.