Here is the full list of all 55 Yaga achievements.
The base game contains 42 achievements, and there is 1 DLC pack containing 13 achievements.
Turn a sickle into a weapon
Call in a spared creature to help you
Give the Gilded Apple to the Tzar
Use the chainfork to pull a few enemies closer
Attach a cartwheel to your arm stump
Lose an arm!
Give the Golden Apple to the Tzar
Attack all old altars
Kill village chickens
Hit the church bell
Reach the end of the game
Remain a blacksmith
Be foolish
Become a royal advisor
Marry a warrior queen
Become the Tzar alone
Witness Yaga's facepalm
Try to flirt a few times
Let Koschei go
Lock Koschei up
Kill an old enemy
Spare an old enemy
Destroy Morozko's Heart
Help Morozko find love
Skip a carefully crafted cutscene
Finish the game without forging any tools
Be really Aggressive
Be really Neutral
Be really Foolish
Be really Greedy
Be really Righteous
Ivan + Poludnica = Love
Crazed man + Poludnica = Love
Polevik + Poludnica = Love
Make the priest rich
Throw a few enemies away
Dig up a burried treasure
Trick the polevik's minions
Help the vodnik live in peace
Make the vodnik rest in peace
Give the Muddy Water of Youth to the Tzar
Give the Water of Youth to the Tzar
Help Kuma Lisa eat Oakvale's chickens
Take the Stuhacs' offer instead of the Magic Ore
Steal the Magic Ore without getting caught
Complete the Loan Shark story arc
Collect all the Trinket Kid's toys
Rescue the Vodnik Mother's kids