Here is the full list of all 18 Arc Defence achievements.
Complete all levels
Complete a level without taking any damage
Complete all levels with five medals
Destroy 100 enemies by one tower
Destroy 100 enemies by acid
Destroy 5 enemies by single bomb
Freeze 5 enemies by single bomb
Drop the leech from the Energy tower
Fully upgrade all towers
Build 1000 towers
Complete a level witout using ability
Complete a level without building attacking towers
Gain over 5000 energy points during one level
Sell a tower entangled in web
Destroy 10000 small enemies
Destroy 1000 medium enemies
Destroy 100 big enemies
Destroy an invisible enemy