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