I think there are some very low-code-intensive ways varieties of this could be implemented. The end-goal here being, of course, something to do after you've already gotten enemy cabal's item, no one is around, and there you are. Yes, you could get some buddies and go try to find X item. But why not more?

There are several big bads in the game. Many are missing their awesome items already. What incentive do I have to risk getting weaponbroke, impaled, or god knows what? So maybe we don't need to code a cabal-opposition calculation into mobs, but something simpler...

What do players really want besides EQ? Luscious edgepoint exploration XP!

So, what if, across all ranks, using a system of bonus calculation based on area rank, and eligibility based on player rank, the imms seed many of the world's favorite "bosses" with exploration XP for killing them one time before you hit a certain rank? With a group bonus!

I love the idea of needing a group to get some xploration XP - instead of just grinding through troll forest, let's make sure we take on the big bad troll at the end, too. He may not have his special item, but we get an exploration xp bonus. Much harder to "mine" this than just walking around the same area you've memorized from other characters.