My comment about the cake was referring to unarmed combat currently. Much of your mitigation comes from buffs and the icing is the magic 18% that never goes away.
The danger with a flat % mitigation system is that you dont have to bother fixing your armor. Why would we want the game to be like that? We have skills that restore armor and it would be far more interesting if you needed you keep your armor up.
I think rage criticals might be fine as they are with tweaks if:
1) armor values were based on type (cloth having value 1.0, leather 1.5, plate 3.0 - or some variation)
2) % mitigation based on armor values were added to the game
3) monsters lost rage when out of combat for 10 seconds
This could alleviate much of the snooze function citan sees in groups. DPS types need to be careful or they pull aggro and get hit. If they take a crit on a rage attack they die. I think I can live with a dps character dying from a rage crit but having tanks be beefy enough to survive them. In fact I kinda want the DPS to die. Why? Because specialized damage characters should not also be tanky. That creates problems where you have the best of both worlds. This is why D&D wizards/rogues (the highest dps classes) don't get to wear plate.
I think we need to backup and ask questions:
A) Does Citan intend for us to prevent strong boss mobs from using their rage attack in order to succeed in certain tough encounters?
Right now the answers is - who cares if the boss has a rage mechanic. I find that boring honestly. That being said WOW went overboard with this and each boss fight was - ok here's the song and dance you do for this boss. That was stupid and boring.
Likewise it would be shitty if you NEEDED an ice mage to make a boss fight smooth to make his rage bar stupidly long with the double +66% debuff thing.
B) Should tanks be the only ones who live through strong hits? (tank definied as specialied armor+ mods for classes like shield or unarmed)
C) is it ok for people to solo in places like GK at the level of the content (last part being very important).
If not then please make the first room be a linked all or nothing pull. Anyone who figures out how to kill 4 mobs at once deserves to solo there.
If the answer is no then as I said before certain skills probably need a rework so you cant stack crazy amounts of dmg reduction.
I don't think it would be as hard to balance as you think. Level 50 armor would count up to X value total offering a % to damage and mobs at that level could be tuned based on changed resistances.
Armor if based loosely on how it is now.... you have 2 options.
1. Unarmed is initially tankier but has no ability to restore armor so you become squish much faster.
2. The armored guy has less base mitigation but can use multiple abilities to restore armor.
I see the game needing to progress so that these are equal options - not one being 5 times better than the other.
If the tank has to worry about using abilities to restore his armor instead of spamming damaging abilities that makes the fight more interesting. If the DPS needs to maybe back off OR possibly try and steal aggro form the tank to keep the tank alive that keeps the fight more interesting.
Right now an unarmed tank has pretty flat % mitigation and that's boring. I feel THAT is what citan wants to avoid. Dynamic % mitigation based on fluctuating armor values would make combat spicy.
The most successful groups in GK are boring. Pull mobs- kill with cheap tricks - repeat. There is very little danger except from the super rage criticals. People are usually rezzed mid combat.
I think it's neat to have an armor bar but it would be so much better if it meant something. Imagine for example if your character sheet told you that at 1000 you had 50% mitigation. If your armor is 50% full then that means you lost half your mitigation (no matter how much armor you have).
Skills that restore armor become way more valuable and combat becomes way more interesting - keep your armor up and be safe or ignore it and potentially die.
One last closing thought that will probably be extremely unpopular - why do animals get to use a shield as an animal? Ok sure fine let them use the mods or whatever but it seems like a cheat to be able to use the armor from a shield while playing an animal (this of course would assume that we change armor to a % mitigation system).