Hero masteries are passive skills which (opposite to the traits and skills) are always the same for a certain hero type, and cannot be changed. Every hero mastery works only against a certain race of monsters.
Monster masteries are very different. They do not belong to a certain guard type, and they only appear in the very last mission and Tree of Life. For example, level 15 of ToL has a Rock Borer boss with Time Slowdown mastery, while level 45 of ToL has a Rock Borer boss with Fear mastery. These masteries don't belong to the Rock Borer monster type, and Rock Borers which can be obtained by the player or dound in missions don't have mastery at all.
Against each type of monster mastery, the is a counter mastery for heroes. For example against the Fear mastery of the level 45 boss of Tree of Life, the Witch Hunter hero has a mastery called Fearlessness. Heroes with these type of counter masteries have purple border around their picture.
The normal hero masteries:
- Inspiration increases the base health of the hero by 80% against a certain monster race.
- Perfection increases the base attack of the hero by 80% against a certain monster race.
- Curse does damage equal to the 30% of the base attack of the hero for 3 turns against every monsters of a certain race. This damage happens after the monster made its counter attack after surviving the normal damage of the heroes.
- Cure heals equal to 80% of the base health of the hero, if the hero hit a monster of a certain race.
- Enemy Knowledge decreases the damage caused by a certain monster race by 11%. (check if it refers to base attack or total in siege, and if it stacks)
- Power Steal decreases the attack power of a certain monster race by 11% (unknown if it applies for the total, or just the base value of their attack. It is very hard to test since pve monsters doesn't have other bonuses, while in sieges the normal attack power cannot be checked unless you know the player you've attacked). (check if it stacks)
- Life Steal decreases the health of a certain monster race by 11% (same question as with power steal). (check if it stacks)
- Sleep puts a certain monster race to sleep for one turn. In other words, monsters of that race will skip their first turn in combat. Doesn't stack.
Each of the above hero masteries exist for all four monster races, with the only exception of Sleep, Cure and Life Steal. No hero has these masteries against demons in the game right now, making demons especially dangerous in Tre of Life.
It is very important, that the masteries calculates only with the base attack/health of the heroes, so bonuses from hero sanctuary, relics, traits, trials doesn't count. For example a max level Berserk hero can have 9004 health, but its Cure mastery will only heal 2792 Hp, since that is the 80% of its 3490 base health.