Here is the full list of all 16 Wildfrost achievements.
Achieve a 3 Win Streak
Stack 5 Block on a single target
Sacrifice 10 allies in a single battle
Stack 20 Shroom on a single target
Stack 15 Snow on a single target
Defeat the Heart of the Storm
Buy 3 Charms from a single shop
Survive an attack from King Moko and win the battle
Defeat the Frost Guardian with a Scrappy Sword
Stack 50 Shell on a single target
Spare the Naked Gnome
Win a Daily Voyage
Feed the Muncher a Consume item
Deal 50 damage in a single hit
Deal 100 damage in a single hit
Win a battle with just your Leader remaining