My main mistake here was during a blast wave wand when I shouldn't have, because I forgot about knockback paralysis (usually it's not a big deal, but here it ran me into 3-4 other paralyzing attacks).
That being said, the Rock density is a pretty frequent issue because there are twice as many attacks as normal. There have been times when the Sappers and Geomancer have attacked at the same time, so there literally is no safe square to move to even in completely open space. More commonly, they will attack within a turn or two of each other, before you get to clear your surroundings. This is the fundamental challenge with this fight.
Just wondering what this illumination would be like. Is it sort of like mind vision? One grievance I've had for a while is that mobs that have mind vision from talents don't actually have a visible mind vision debuff from those talents, so you can't very well track the effect as a player, which seems a bit odd to me.