Here is the full list of all 13 Forests, Fields and Fortresses achievements.
Сomplete the first level
Complete the fifth level
Complete the eleventh level
Complete the seventeenth level
Complete the thirtieth level
Complete the twenty-third level
Complete the thirty-fifth level
Complete forty-two level
Complete all levels
Complete the game season in Adventure mode
Use any spell in Adventure Mode
Level up in Adventure Mode
Create a region consisting of 40 cells in Adventure mode