Say you got the chance to be the game director, and you decide to do what you can to make monster encounters range from easy to challenging while remaining balanced and fair.

What kind of damage would you have a fairly challenging monster type deal in a T16 map? Keeping in mind that you have no control over how much defenses the players build - you have players ranging from 3300 HP deadeyes to fairly tanky melee players to gigatank juggernauts. What kind of damage should the monster deal that the game doesn't feel unfair to the deadeye player but not trivial to the other 2 players? And will you account for map mods, which can sometimes add 0 damage to the map but can also sometimes triple the amount of damage the player takes?

And once you've figured that out, how will balance the enemy life? The players might have anywhere from tends of millions of DPS to having less than one million. Where do you put monster life so that it's not trivial to the players going all out on DPS minmax, but not completely unfair to players who are playing more balanced, less DPS oriented builds?

I'd like to hear people's thoughts on this, since so many readily criticize the state of the game, but few seem to have solutions. You'd have to also remember that it's a game of many audiences, where some would want the game to be more challenging and some would have it be easier.

edit: some of y'all really like downvoting discussion threads don't ya