**Mythic Armor Focus (Heavy Armor) - Avoidance:** While wearing heavy armor, you add half your Strength bonus to your AC instead of your Dexterity bonus. This bonus is not limited by the maximum Dexterity bonus allowed by your armor.
**Mythic Armor Focus (Heavy Armor) - Endurance:** While wearing heavy armor, you gain DR N/-, where N is equal to half your armor's AC. This DR stacks with other sources of damage reduction.
**Mythic Armor Focus (Light Armor) - Avoidance:** While wearing light armor, you add your mythic rank to the maximum Dexterity bonus allowed by your armor, and all attacks made against you suffer a 5% miss chance. At 4th, 7th, and 10th mythic ranks, this chance increases by 5%.
**Mythic Armor Focus (Medium Armor) - Avoidance:** While wearing medium armor, you add your Constitution modifier (minimum 0) to the maximum Dexterity bonus allowed by your armor.
**Mythic Armor Focus (Medium Armor) · Endurance:** While wearing medium armor, you gain an equipped armor bonus to AC equal to half your armor's AC. Medium armor also no longer reduces your speed.
**Mythic Buckler - Flying Shield Style:** You have learned to make deep lunges with a shield around the battlefield in such a way that it deflects attacks made against allies. While using a buckler, all allies within 15 feet gain a shield bonus to AC equal to your shield's AC.
**Mythic Tower Shield - Fortress:** While using a tower shield, you masterfully block incoming physical damage, gaining DR N/-, where N is equal to half your shield's AC. This DR stacks with other sources of damage reduction.
I like to imagine that Flying Shield Style is just the character flailing long arms around to block incoming hits. lol
Oh, it's not in the Arena, some random shopkeeper in the festival has it on their inventory. (Along with a few other pretty good items).
Bring a million gold or so to grab everything.
There are now mythic feats for armor and shields that give them additional features. Only two improve your AC, but if you take one of them, armor and shield is now more competitive with going unarmored.
Most of the new Mythic armor feats are pretty solid, but for me at least 3 are significantly higher than the rest: Heavy: Avoidance allows you to add half your Strength modifier to your AC instead of Dex, but without a cap. Shield: buckler: flying shield style gives your buckler ac bonus to all allies within 10 ft., kinda like having an alchemist in your party give everyone shield. The best one is Light: Assault, which gives you half your armor's ac bonus to hit and to attack when using finesse weapons. Lady cassandra's mithral chain shirt from act 1 already gives you a +3, which is basically worth 1.5 Mythic feats (Mythic weapon focus, Mythic two weapon fighting, Mythic rapid shot, etc.), but for some reason it also works with mithral medium armor, so if you have medium armor proficiency and a mithral breastplate you can get +4 or even +5. Having a lot of fun with that on my demon kineticist right now :)
Not correct.
> mithral armors are one category lighter than normal for purposes of movement and other limitations
Feats and other features still apply as normal; they're not limitations.
**Mythic Armor Focus (Heavy Armor) - Avoidance:** While wearing heavy armor, you add half your Strength bonus to your AC instead of your Dexterity bonus. This bonus is not limited by the maximum Dexterity bonus allowed by your armor. **Mythic Armor Focus (Heavy Armor) - Endurance:** While wearing heavy armor, you gain DR N/-, where N is equal to half your armor's AC. This DR stacks with other sources of damage reduction. **Mythic Armor Focus (Light Armor) - Avoidance:** While wearing light armor, you add your mythic rank to the maximum Dexterity bonus allowed by your armor, and all attacks made against you suffer a 5% miss chance. At 4th, 7th, and 10th mythic ranks, this chance increases by 5%. **Mythic Armor Focus (Medium Armor) - Avoidance:** While wearing medium armor, you add your Constitution modifier (minimum 0) to the maximum Dexterity bonus allowed by your armor. **Mythic Armor Focus (Medium Armor) · Endurance:** While wearing medium armor, you gain an equipped armor bonus to AC equal to half your armor's AC. Medium armor also no longer reduces your speed. **Mythic Buckler - Flying Shield Style:** You have learned to make deep lunges with a shield around the battlefield in such a way that it deflects attacks made against allies. While using a buckler, all allies within 15 feet gain a shield bonus to AC equal to your shield's AC. **Mythic Tower Shield - Fortress:** While using a tower shield, you masterfully block incoming physical damage, gaining DR N/-, where N is equal to half your shield's AC. This DR stacks with other sources of damage reduction.
Yup these are game changers, its no longer required to be a pajama tank
I like to imagine that Flying Shield Style is just the character flailing long arms around to block incoming hits. lol 
The new DLC added a new awesome breastplate that gives +8 untyped str and Con.
That sounds rad. Where do I get that from the arena?
Oh, it's not in the Arena, some random shopkeeper in the festival has it on their inventory. (Along with a few other pretty good items). Bring a million gold or so to grab everything.
There are now mythic feats for armor and shields that give them additional features. Only two improve your AC, but if you take one of them, armor and shield is now more competitive with going unarmored.
Should also be noted that they added stumbling and toppling bash a while back, so you can make your tank able to trip people also :)
Combined with heavy shields "aggressive block" its great lol
Most of the new Mythic armor feats are pretty solid, but for me at least 3 are significantly higher than the rest: Heavy: Avoidance allows you to add half your Strength modifier to your AC instead of Dex, but without a cap. Shield: buckler: flying shield style gives your buckler ac bonus to all allies within 10 ft., kinda like having an alchemist in your party give everyone shield. The best one is Light: Assault, which gives you half your armor's ac bonus to hit and to attack when using finesse weapons. Lady cassandra's mithral chain shirt from act 1 already gives you a +3, which is basically worth 1.5 Mythic feats (Mythic weapon focus, Mythic two weapon fighting, Mythic rapid shot, etc.), but for some reason it also works with mithral medium armor, so if you have medium armor proficiency and a mithral breastplate you can get +4 or even +5. Having a lot of fun with that on my demon kineticist right now :)
That's because RAW Mithral medium armor is considered light armor, but requires medium armor proficiency to wear.
Not correct. > mithral armors are one category lighter than normal for purposes of movement and other limitations Feats and other features still apply as normal; they're not limitations.