Here is the full list of all 16 Defend Your Crypt achievements.
Finish all levels.
Kill 3 thieves with the water trap at the same time.
Complete one level without speed up.
Complete one level with only 1 gold unit left.
Watch two thieves doing a High Five!
Make 1 thief sad.
Kill 200 thieves with a crusher trap.
Burn 30 thieves.
Kill 10 thieves.
Kill 100 thieves.
Kill 150 thieves.
Kill 250 thieves.
Kill 500 thieves.
Kill 1.000 thieves.
Kill 2.000 thieves.
Complete one level without losing any gold.