Tanking with Flat Mitigation vs Percentage Mitigation and Enemy Critical Hits

[Aionlasting]

While I like the idea of rewarding preparation, I don't agree with some of the examples you've given. Players being "Forced" to bring a certain class to counter specific mobs is something I dislike heavily in MMORPGs because it's just a gimmicky way to force a certain class into every party, usually because no one would bring it otherwise or it becomes incredibly powerful. There are actually a few enemies in game which are close to this, such as the Beholders at the bottom of Gazluk which require a Druid to Rotskin them, but Rotskin just cuts their defense in half, rather than being impossible/extremely difficult to destroy without it.

Using your example of evasion mobs, I believe a better way of rewarding preparation would be to reward players for getting accuracy instead of bringing a certain class, because there are a lot more ways to go about it. For example players could build accuracy on their gear, bring accuracy boosting items, use skills which have an accuracy bonus or maybe a dedicated support could boost everyone's accuracy/lower the enemy's evasion. This makes players have to prepare, but gives players options rather than forcing them lug over a player of a specific class. You could make it so one skill is particularly good at buffing the party's accuracy and that's great, but it shouldn't ever be the only option.
I believe this may be the intended mechanic of Dark Chapel... but currently the calculation for hit chance is bugged and it's pointless to build accuracy on your character to counteract the evasion mobs have there. Any evasion a mob gains through a buff/player debuff cannot be mitigated with accuracy, and every mob in Dark Chapel gets its evasion this way.

Also I do disagree about tanks being unhelpful. Even before the crit change tanks could make going through dungeons significantly faster, and even with crits a proper tank can shrug off crits. The issue is just that what falls under "a proper tank" is extremely limited due to percentage based mitigation being so limited in the game hence why I made this thread in the first place.

I suppose you could build the requirement into the gear. The other solution would be to give multiple support classes the ability to remove armor (such as rotskin but obviously the name would different to fit the class it belongs to), the ability reduce attack speed, the ability to weaken evasion etc... that way no one specific support class is required because the abilities are shared amongst the support classes. So say the game has 4 or 5 support classes, give 2 of them one ability that's shared, give the other two another, etc... that way to you spread it across.

In the same vein, sprinkle the ability to mitigate damage across the various tanking classes.

tldr; spread the love around, allow multiple classes to peform similar functions that way no one class is always required but multiple classes can peform the needed function (i.e. debuffing armor, attackspeed, evasion, etc..)