Having the gameplay incentive (or requirement) to change from one build to another to better adapt to an encounter’s specific challenges. This is a catch-all for anything that deals with build, including gear, skills, traits, and nourishment.

The problem with your suggestion is that it wouldn't encourage build diversity. It just herd parties to go from zerker to soldier to cleric to whatever. I like the suggestions, but it isn't enough. I want real build diversity where each and every players have a different role to defeat the enemy.

My suggestions:

1) Let each mob group do everything. From Boon removal, reflect, protection, blocking, CC, burst damage, pressure, etc. Not every mob can do this, so condi/boons/attacks spreads out through the mobs.

• This way, if I play a Condimancer, I am useful throughout the dungeon consistently.
• I will need to strategize which mobs I need to take down. If I simply zerker stack, mobs will simply remove the stability buff, CC the party and then wipe the party.
• To make each encounter varied, how they apply each attack will be different. A leap from Scavenger Graveling can cause confusion/Bleed/Torment, another Scavenger Graveling can cause Stun and grant nearby allies stability on hit. A scavenger Graveling blast finisher causes knockback, another can cause poison and massive damage.

2) Let mobs heal.

• By giving mobs healing, players have to interrupt.
• Mordrem Mender made healing possible even though damage interrupts it. Which is fine because PvE world shouldn't be extremely challenging.
• Also, let mobs run away and self-heal. The mob's pathfinding would simply go straight to the place where they last initiate combat instead of directly behind so that players are incentivized to charge straight through instead of pulling mobs.
• Makes poison useful.

3) Hate/Weaknesses

• When a mob gets attacked by a thing it hates: It grows stronger and more aggressive, making the mob encounter harder.
• This is my response to singling out mobs It is also a way to force the meta out.
• When a mob gets attack by its weakness. The attack is more effective on them.
• Example: A mob hates being confused. When a mesmer puts confuse on it, the mob will gain berserk which will increase his damage, increase toughness and lower the skill cooldown, A mob is weak to confused will gain 3 more stacks of confused when a mesmer puts confuse condi on it.
• Autoattacks/passives will not trigger hate/weakness.
• This hate/weakness system will change through each mob. Also, devs can use this to change the meta consistently. If players are being too zerker, Devs or the program can simply make the mobs hate being damaged too much. If condi become the meta, mobs will hate bleed/poison/torment/burn.

4) Elite Mobs/Bosses

• This is my response to making toughness/Vitality stats more useful.
• This is designed so that players will split off from each other.
  
• Players with high toughness tank the elite mob so that their party can defeat the other trash mobs.
• Elite mobs do more a lot more damage to players with low toughness, but a lot less damage to players with high toughness. All Elite mobs also do cleaving and have high attack speed, so stacking is a death sentence. However, if all the mobs accompanying the elite mobs are dead, the elite mob will do less damage to players with less toughness and have less attack speed. Elite mob's telegraphed attack still do a lot of damage and may even instagib tanks. So tanks still need to dodge skillfully. Toughness is needed to counter the high pressure from bosses.
• Condi elite mobs do less condi damage to players wearing vitality.
• Regular mobs still do decent damage to players with high toughness, so high toughness player still can't tank everything like the traditional MMORPGs.
• Elite mobs do not have hate/weakness.
• Knockbacks, pull, fear, taunt does not affect defiance, but does not interrupt elite mob. This is to make it easier to push elite mobs away from the other mobs.
• Bosses can act like Elite mobs.

5) Nerf ressing/Buff healing power

• This is my response to making Healing power more useful. Also to encourage spreading out instead of stacking.
• 1 player ressing 1 player see no change to ressing. 2+ players ressing 1 player gets res heal nerfed.
• For every player that res a downed player, each player gets a 50% res reduction. The first player have 100% res effectiveness, the second player has 50% res effectiveness, the third player has 25% res effectiveness and so on.
• If players don't die, healing power isn't required at all.
• Since it is synergetic with party healing, Having healing traits can be useful. But not required. I expect the meta to not use healing traits at all since they are so bad.

6) Remove/nerf a lot of these mobs and then place the challenging ones in strategic places.

• The challenging mobs are unskippable, but there are a few in number. It is always accompanied by a boss/elite mob.
• The trash mobs are skippable but they are very easy to kill which will take around a few hits to kill them. They exist to make the dungeon look populated.

Conclusion:

There will still be a meta build compilation, but not every profession can do everything all at once. Instead of waiting for a mesmer. Parties can simply take a necromancer for boon removal even if the meta says they are weaker than mesmer. Parties can take a tanky Engineer instead of waiting for a tanky warrior to tank Elite mobs or bosses.

My vision for a mob encounter is simply that the party charge in, the party split up, the tank distracts the tougher ones, the rest of the party fights the weaker mobs. They look for the weakness and exploit it and try to avoid enraging the mobs. The party looks for signs that mobs will use a devastating move. The boon removers remove boons that the enemy stacked themselves with. I want a dungeon party that I thought the game would play like at launch when no one knows about the zerker meta.