Here is the full list of all 55 Farabel achievements.
The base game contains 50 achievements, and there is 1 DLC pack containing 5 achievements.
Complete the Tutorial
Win the battle The Black Mountains without losing any unit.
Win the battle The Forest in 13 turns or less.
Win the battle The Flood in 12 turns or less.
Win the battle The Prisoners without losing any unit.
Win the battle The Ancient Gods in 9 turns or less.
Win the battle The Goblin Sappers in 12 turns or less.
Win the battle The Walls without losing any unit.
Win the battle The Citadel without losing any unit.
Win the battle The Gates of Farabel in 9 turns or less.
Win the battle The Catapult in 25 turns or less.
Win the battle The Bridge without losing any unit.
Win the battle The Ambush in 11 turns or less.
Win the battle The Origin without losing any unit.
Complete the Campaign
Kill an enemy unit
Unlock all the stars
Win all the unlocked battles
Kill 100 enemies
Kill 400 enemies
Kill 1,000 enemies
Kill a enemy with a counter-attack
Kill 5 enemies at once with the Lightning ability of Cendor
Heal 25 HP at once with any healing ability of the High Priestess
Heal a total of 250 HP with any healing ability of the High Priestess
Heal a total of 1,000 HP with any healing ability of the High Priestess
Heal 5 units at once with the Soothing Fire ability of the High Priestess
Kill a total of 30 enemies with the catapult and the ballista
Kill a total of 100 enemies with the catapult and the ballista
Kill 3 enemies at once with the catapult
Remove 3 HP from a unit with the Turn Back Time ability of Cendor
Restore 3 HP to a unit with the Turn Back Time ability of Cendor
Kill 50 trolls
Win 30 battles
Battle The Black Mountains: Kill Azuk
Battle The Forest: Win the battle without getting any unit asleep
Battle The Flood: Win the battle without opening doors
Battle The Prisoners: Kill an opponent with an enemy catapult shot
Battle The Ancient Gods: Kill the Boss destroying only one of the two pylons
Battle The Goblin Sappers: Kill a total of 80 goblins in a battle
Battle The Walls: Win the battle by preventing enemies enter the stairs
Battle The Walls: Kill a total of 40 enemies in a battle
Battle The Citadel: Kill an enemy with the explosion of an explosive goblin
Battle The Citadel: Kill a total of 50 enemies in a battle
Battle The Gates of Farabel: Kill Orak without the Turn Back Time ability of Cendor
Battle The Catapult: Summon The Elemental in the first Turn and keep it alive until the end
Battle The Bridge: Kill 4 enemies at once with the destruction of the bridge
Battle The Bridge: Kill a total of 40 enemies in a battle
Play the Orcs
Reach the Emperor rank
Battle The Origin: Kill a Hell Beast fairly
Unlock the Golden Badge in Defense mode
Unlock the Golden Badge in Classic mode
Win a battle against humans in Classic mode
Kill 5,000 enemies