Here is the full list of all 20 Bosorka achievements.
The base game contains 15 achievements, and there is 1 DLC pack containing 5 achievements.
Defeat the location boss
Kill 5 enemies with less than one heart
Kill 10 enemies with a broom
Kill 100 enemies
Fall into the sacrificial pit in Whisperer Grove
Kill 5 elite monsters
Complete one level in 7 minutes
Open all chests on one level
Collect 30 runes
Collect 20 thousands gold coins
Research a spell in the well
Die from the location boss
Collect 13 souls
Complete the game for the first time
Free 5 companions from the cage
Burning, kill three Litavets with a dash during one run
While under the Curse of the Old Rat, kill any boss using the Viper's broom ability
While under the Curse of the Four Winds revive 10 fallen companions during one run
Free all imprisoned demons across all locations during one run
Complete the game under the Curse of the Black Book