Hero Masteries, or just Masteries, are universal enhancements that increase Attack, Defense and Health for any hero in the game.
Masteries are available for any hero 4★ and level 80 and higher.
There are two types of Masteries: standard ones and Ancient Masteries. You level up the standard Masteries like a Skill Tree, linearly until it unlocks an Ancient Mastery.
Masteries (standard)[]
The standard Masteries will level up the base stat for a hero in Attack, Defense, or HP. Leveling up Masteries requires Fragments of Emptiness, which are earned as a reward for completing levels in Wild Lands.
Ancient Masteries[]
Ancient Masteries are special passive skills that are unlocked after learning all of the standard Masteries for a specific base skill. A hero's Ancient Mastery is an effective passive skill that is triggered when certain conditions are met in combat.
Learning Ancient Masteries will require Element Fragments, which can only be found inside boss chests in Wild Lands, or bought as an in-app purchase.
A Hero can learn every Mastery in the game, but may only have one active at a time:
Last Breath — when a player's HP drops below 25%, runes of the Hero's element will no longer grant mana to enemies for the next 2 turns. Works only once per battle.
Defiance — at the start of the battle, damage from the hero's Special Skill ignores 15% of the target's defense. This effect wears off after the Special Skill is used the first time.
A Blessing in Disguise — if the hero's Special Skill boosts the attack/defense of allies, one random Hero on your team will gain a buff that allows them to convert burned mana into gained mana x2, for the next 2 turns. This buff lasts until it is triggered, or until the end of the battle.
Martyr — When this Hero dies in battle, two random enemies receive a debuff that blocks any mana gain for the next 2 rounds.
Smith's Mercy — Basic Equipment stats are increased by 10%.
It's important to re-iterate that Masteries and Ancient Masteries are the same for Heroes of all Groups and Classes. Also, Ancient Masteries can be changed at any time.
Changing it the first time is free, and all subsequent changes will require Gems 
.