Here is the full list of all 21 Frost achievements.
Finish The Leader scenario
Win a game with one Health Point
Travel 40 times in Endless
Win on hard difficulty
Win a game without any Fatigue card in your deck
In medium difficulty, win the game witout finding the Refuge
Win on medium difficulty
Win a game in any mode
Win in easy mode
Win a game after having had the Frost counter on 1
Finish The Hunter scenario
Finish The Tracker scenario
Finish The Meditator scenario
Win a game witout any Survivor in your deck
Win a game without any Idea in your deck
Finish the Priest scenario
Finish the Frigomancer scenario
Finish the Skeptic scenario
Finish the Recruiter scenario
You won on Impossible difficulty :o Congrats!
Finish the Guide scenario