The place that I die the absolute most is at the south end of a third arena, and the reason I die is because I can't clearly see my enemies. On the first two arena rooms I can just avoid spending time with my view blocked, but add those spikes and my movement choices are limited. Failing at T3 phantoms or rocket puppies is one thing, I just need to get better or get better equipment, but failing because I can't see what's happening is just frustrating. (And it happens to others too... unfortunately, health-reviving a teammate in that blindspot is pretty much impossible to do until the room is already cleared. Sometimes you can leave the last enemy or two of a wave behind and sneak it in, but it's very risky when there's a mob, especially a mob with ranged attacks.) I can't get better at seeing through walls unless the developers make the walls and gates that block the view of your knight transparent, so please do.
There are also places, like the gold key in Wolver's Den, that are completely blocked by walls. Most of those corners you can just avoid going into, and the same problem happens to a lesser extent in various gate-trigger mazes.
A less general solution would be to simply turn the arena levels 90 degrees, then there wouldn't be a blind spot there, and I would be very grateful, but there would still be a blind spot in other levels. None quite as bad as that.