How about one where once engaged in battle, you lose 1 stack of NV (If present) for every minute its alive? Maximum of 5 minutes to kill it (and you can lose up to 5 stacks of NV) from first attack made to the death of the mob. If you kill it in 2 minutes and say you have 3 stacks you gain extra stacks for the minutes you killed it in.
Are you posting these in the official forums/reddit as well? I'd definitely upvote this idea there.
It's something relatively easy to test and implement (I guess) and it's a great idea to add variety to combat - which is something everyone who has 400+ hours would appreciate, I'm sure.
I will be posting these in the official forums soon just have to clean up the tables; make assumptions on how what I've come up with would mesh with current affixes. I'm already out of steam because the other things I think of that I believe aren't overly complicated to add to the game feel redundant.
I have to disagree with the idea that monster affixes don't have much synergy. Granted, some kind of counter each other, and are almost lucky accidents. For instance, when you get an elite pack with Mortar and Vortex. Best way to stay out of the Mortar's range is to stay in close, which Vortex helps you do. Another example, Nightmare and Vampiric. They restore their life by attacking you, but Nightmare sends you far out of their range, unless they have a ranged attack which they don't always.
Then again, some affixes are perfect for keeping you grounded and exterminating you. Waller-Arcane-Plagued? Or Jailer-Frozen-Molten-Plagued? Sure, if you have skills equipped like Vault, Teleport, Leap or Spirit Walk, you have some easy method of escape (not always guaranteed, depending on the exact affix), but if you have a build that works differently, those kinds of combinations could be deadly.
Granted, all in all, if you do enough damage, affixes don't come into play because you're killing faster than you're being put in danger. I mean, that's part of (or mainly) the reason people made such a stink over Reflect Damage. All people were doing was stacking DPS and Crit, and since there was no visible indicator of the affix, they either had to STOP hitting skill buttons for all of two seconds to READ the line of affixes (I know, god forbid), or they would one-shot themselves. Of course, now that's been modified...
Personally, I would rather there be MORE affixes that forced players to take half a breath to read and apply some thought and strategy before mindlessly blindfiring into groups of bad guys. Having to kill champions in particular order? Hey, that'd mean...wait for it...BUILD DIVERSITY! :-) Either vary up your skills to include single-target damage, or learn to kite and separate enemies so one can be killed at a time. Forcing a player to kill an elite pack, or lose their NV stacks upon death? Seems to me like that would make just about any combination twice as dangerous (yes, I said double it but in a different way).
Definitely in favor of affixes that make the others work differently as well. Some affix that significantly raises the reward for winning the battle, but that makes any other affixes attached way harsher. An affix that randomly spawns that adds two other affixes in temporarily, or hell, even an affix that randomly switches to something else. You could be rolling on a vampiric pack, suddenly it switches to RD and boom...dead. Something you need to watch for before hitting skill buttons.
If these aren't implemented, definitely looking forward to a wider variety. I take the current batch of affixes seriously as it is, but a wider variety, more dangerous effects, and really creative stuff to both randomly boost reward AND danger, are all healthy things for the game as a whole.