Here is the full list of all 50 Batbarian: Testament of the Primordials achievements.
Trust Twigs to join your team
Defeat the three headed lich in the ruins
Have Pip do an elemental strike on an enemy weak to it
Get the dash boots and the power ring
Oops. A short lived companionship.
Defeat the quivering ancient
Have Drai Lez join the team
Read something in the dungeon
Defeat the Goddess and her undead servant
Defeat the pesky ghost for real this time
Defeat Cobalt
Defeat the Ogre Leader
Defeat Drai Lez after his betrayal
Defeat the demon Vorga
Defeat Lamara
Spare the drakin
Kill the drakin
Have Rowr join the team
Discover the Ethereal Palace...
Discover the truth
Pip is on fire
Pip is frozen now...
Get all heart upgrades
Find all the maps
Trick the imps
Bribe your way in twice
Recover the ghost's memory
Save Friffle and his kids
Collect 3 stone fragments
Get Friffle's kid's name right
Beat the game (Ending C)
Beat the game (Ending B)
Beat the game (Ending A)
Hit that annoying lever
Reach the ogre fortress factory's entrance without being caught once.
Never miss a chance to say you hate magic
Find 10 gems
Find 25 gems
Find all gems
Carry 30 stones
Find 10 upgrade satchels
Collect 10 Ogre draughts
Collect 10 iron skin potions
Collect 10 awareness potions
Unlock all bestiary entries
Loot 100% of the chests
Carefully beat a boss without getting hit
Reach the final boss and escape the cave victorious in under 3 hours
Reach the final boss and escape the cave victorious without dying
Complete the puzzle piece and arena goblet trophies in Forgotten Roots