Asking about Mode Assassin Helm (Black)

Hello guys! Mistersnow here. Dropping a vanity is rare, i know how rare it is. but this vanity is questionable. Unlike Dev Skull, Mode Assassin helm Is so expensive becaus of it's rarity. Yeah the rarity itself. Some said it is droppable at Endless war (wave 20) which is harder as expected. Some said it is droppable in winter crates(which is true but only in winter season) but the question is how can we drop this vanity without openong some winter crates? And also is there any proof of it? I saw koenji's video. Yeah it is possible but no one proves it. Hope you guys answer this.