Here is the full list of all 18 Lost Artifacts: Soulstone achievements.
For defeating the Villain
For completing all levels with 3 stars
For collecting all trophies
For stopping time
For the Second Fountain
For completing 15 levels with 3 stars
For restoring monks’ altars
For speeding up construction
For destroying towers
For activating an altar
For getting rid of the Wicked Thief
For restoring the water wheel
For speeding up the atlanteans
For the First Fountain
For completing 5 levels with 3 stars
For restoring a statue
For constructing a building
For clearing one roadblock