cynthialee wrote:"This monster and his entourage are Elite Monsters and thus defend on all shields"
That simple change alone will make bosses extremely difficult targets.
To be honest I'm less keen on that suggestion for a couple of reasons. Firstly I think, having run the numbers, I agree it would make them extremely difficult, in fact it makes some bosses & entourages too persistent, even a Boss, say Gargoyle with a couple of Chaos/Dread Warriors, using all shields for defence and you'll be hacking away all day (using up your quarters, like it!)
The other reason is the 'simple' bit.
I proposed the following on a different thread

= "White Skull" lose a BP unless blocked by a shield

= "Black Skull" lose a BP unless blocked by a shield plus pushback opponent

= "Shield" blocks a skull
I think that is simpler than

= "Skull" lose a BP unless blocked by a shield

= "Black Shield" used by many monster as a shield that blocks a skull, but not all as some monsters use White Shields only for defence and some use both Black and White Shields

= "White Shield" blocks a skull for Heroes and some monsters (and some other monsters that also defend on Black and White Shields)
As a GM I do have a crib sheet, but I force myself to keep it to a single A4, so any modifications that I introduce that I think may be a candidate for inclusion on my crib sheet (like the Combat Dice modification above) have to earn their slot, and I could see myself having to pause and look up which monsters/entourage/bosses defend on which shields in a given situation so I would resist that mod personally.