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