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