Here is the full list of all 25 Mistral achievements.
Kill the Giant
Kill the Light Bearer
Kill the Dragon
Kill the Grim Reaper
Kill the Red Demon
Kill the Dark Knight
Obtain 100 weapons
Obtain 100000 Gold
Unlock 2 different talents in the Power Book
Unlock 8 different talents in the Power Book
Collect 1000 Chests
Free 100 villagers
Win a game in Easy mode
Win a game in Normal mode
Win a game in Hard mode
Win a game in Very Hard mode
Play a multiplayer game
Win a multiplayer game
Deal more than 3500 damage in a single hit
Kill a boss without losing HP
Fully fill your inventory
Have more than 1200 HP
Have more than 900 Shield
Have more than 45 Armor
Have more than 100% critical chance