Here is the full list of all 50 Delve Deeper achievements.
Play on the hardest AI difficulty
Turn in 'The Spammish Inquisition' three times
Turn in 'Fistful of Spiders' three times
Sell 1000 relics to the Ooogler
Kill 50 dark diviners
Kill 100 dark traitors
Kill 50 dragons
Collect 10 runes
Kill 100 gnome gnights
Kill 25 purple goblins in one match
Kill 25 mimics
Collect 10 fossil relics
Collect all original relics
Win a match without digging any new tunnels
Kill 5 goblin kings
Kill 10 cubes or jellies in one match
Kill 500 enemies
Critically hit 200 enemies
Kill 25 green goblins in one match
Recieve 5000 HP of Fairy Healing in a match
Kill 200 goblins
Kill 25 gray goblins in one match
Collect 10 weapon relics
Kill 10 dragons in one match
Kill 100 slimes, cubes, or jellies
Win with a team of five miners
Win a match by collecting only mithril
Kill a Dragon with a Scout
Collect 10 armor relics
Win with a team of five scouts
Win a match without mining anything
Deposit 50 gold in the Gnome Bank in a single match
Win with a team of five fighters
Kill a Fighter with a Scout
Play a multiplayer game
Collect 10 booze relics
Sell 20 relics to the Ooogler in a single match
Collect 10 book relics
Get a Fighter killed by a Green Slime
Turn in 'The Pink Pangolin' three times
Turn in 'Jagrath's Balls' three times
Kill 100 enemies
Play a custom level
Create a custom level
Kill a Fighter with a Miner
Turn in a bogus relic
Play a two-player match between the Red and Blue teams
Kill 10 gnome gnights
Turn in an epic relic
Play through the tutorial