I HAVE HAD THE EPIPHANY!

It's the timing! I know there are a LOT of mechanics the higher you go where it looks like "there's nowhere that isn't orange," but it's about the order of explosions. This is one of those! It finally hit me that there's a significant delay between when the spread mechanic starts its tell, the knockback goes off, then you have seconds to execute the spread! I was often getting DOT'ed because I felt I couldn't go right into the center because "it says spread, I have to spread," but you don't until AFTER the knockback! It's a thin window but so is every overlapping mechanic, this is just a different version of it! It's the timing, that's the key!