Here is the full list of all 13 Defend the village from goblins achievements.
Survive the first Horde
Defeated a Hobgoblin
Defeat 10 hordes
Defeated horde of Warriors
Defeat 20 Hordes
Defeat 30 Hordes
Defeat 40 Hordes
Defeated a Goblin Champion
Defeat 60 Hordes
Defeat 70 Hordes
Defeat 80 Hordes
Defeat 90 Hordes
Defeated 100 Hordes