There are some parts of the game where it’s REALLY hard to tell when there’s gas around (particularly when the less-than-stellar audio is acting up) with the Black and White screen filter, such as the finale event in Convocation of Decay. Some sort of more noticeable graphic (or a color tweak) could help mitigate that.
Not just the Wound filter, but any filter at all. Shade/HS/RV invisibility, Zealot’s speed buff, Slayer’s speed buff… All put out a screen filter that in some places hinder general visibility quite a lot (Athel Yenlui, I’m looking at you), and in many (most?) places hinder your ability to discern gas clouds and even troll bile puddles. I have fallen a few times as Slayer because of that.
Also it doesn’t help when the splatter texture on the ground can blend into the ground texture in B&W, or just clip into the ground completely, making it almost impossible to gauge the area the gas is covering.
There are some reaaallly frustrating places to be under Slayer ult especially I find. Being half blind and totally deaf to special/horde/boss alerts is a pain.