Here is the full list of all 39 Digs achievements.
kill 100 rockbrain
kill 100 tunneler
kill 10 big mage
kill 100 mage
kill 10 greeny
kill 100 speedy
kill 100 nightwing
kill 10 prof
kill 100 nurse
kill 10 mcspawnmore
kill 100 chesty
kill 100 shattered
kill 100 gladiator
build 300 regular trap
build 300 regular crystal
build 300 regular orb
build 50 laser
build 50 lava trap
build 50 piercing
build 20 portal trap
build 50 poison trap
build 100 frost orb
build 100 frost trap
build 100 frost crystal
build 100 smart crystal
build 20 ranger
build 100 zapper
play 100 easy waves
play 100 normal waves
play 100 hard waves
pass 5 easy modes
pass 5 normal modes
pass 5 hard modes
dig 500 dirt blocks
dig 500 crystal blocks
dig 500 orb blocks
dig 500 trap blocks
dig 500 card blocks
dig 300 mysterious blocks