Here is the full list of all 13 A Healer Only Lives Twice achievements.
Defeat Troll Thug
Attack three enemies at one time by using Courage skill
Defeat Golem
Cure Petrification or Poison by using items or skills
Game over
Enter Tier 3 (MAIN Mode or EX MAIN Mode)
Learn all skills
Defeat Minotaur
Defeat Gryphon
Unlock all upgrades
Complete MAIN Mode or EX MAIN Mode
Complete TRIAL Mode
Complete EX MAIN Mode