Here is the full list of all 15 One Troll Army achievements.
Survive at least 30 waves without losses at the Survival mission.
Kill the most powerful of the bosses.
Complete all remaining quests.
Hire 30 mercenaries.
Upgrade all buildings and towers up to level 3.
Upgrade goblins to the maximum level.
Upgrade tower weapons to the maximum level.
Earn 10000 materials in total.
Improve all troll skills to the maximum level.
Spend 10000 gold on resources.
Earn 10000 coins in total.
Kill 1000 enemies.
Upgrade all buildings and towers up to level 2.
Complete all buildings and towers of the fortress.
Kill 100 enemies.