I can’t add screenshots here apparently so what I’m saying here won’t mean anything to someone who doesn’t play DK.
I think we’ll all be able to agree that defile adds a shadow and makes any visual effect much harder to see. In this instance it doesn’t feel terrible but in crowded pulls, things like small circles can get impossible to see especially if there are a lots of targets in your defile/there is a lot of melee etc. Death and Decay is much more visible than Defile simply because red pops out against a lot of colors.
I think Blizzard did a great job with these new visuals as they clearly define the area really much better than it used to be; but Defile sure does not a change either to itself or how it interacts with other vfx.