Here is the full list of all 54 Fallen Enchantress: Legendary Heroes achievements.
Recruit Mausolos
Play for 100 hours.
Win as Gilden.
Win by casting the Spell of Making.
Get a city to level 5 in one game.
Recruit Tuatha
Create a custom sovereign.
Reach level 15 with a champion.
Design a unit.
Play for 40 hours.
Win and have at least 3,000 population.
Win as Resoln.
Win by forging an alliance with all players.
You've managed to slay Abeix!
Complete 10 quests in a single game.
Not since Peter MacNicol has one been slain!
Recruit Gallowman
Buy an item from a shop.
Play for 20 hours.
Recruit Ascian
Recruit Kasst
Control 5 cities in a single game.
Tap 10 resources in a single game.
Play for 10 hours.
Defeat a faction.
You defeated a sovereign in battle!
You have captured an enemy city!
Reach level 5 with a champion.
Play for 5 hours.
Complete a quest.
Explore 10 goodie huts in a single game.
Your Fame has lead a hero to your cause.
You killed a monster!
You have defeated an army!
All nations start with one.
You've managed to slay Delin!
You've managed to slay Morian!
You've managed to slay Torax!
You've managed to slay Vetrar!
Awarded for completion of the Legendary Hero scenario.
Win by defeating all of your opponents.
Win by completing the Master Quest.
Win by having the highest score by the turn limit.
Win as Altar.
Win as Pariden.
Win as Tarth.
Win as Kraxis.
Win as Magnar.
Win as Yithril.
Make 1000 gildar from selling items in shops.
Recruit Raza the Wild
Recruit Nen Ratcatcher
Win as Capitar.
Win as Umber.