Here is the full list of all 54 Lennas Inception achievements.
Max out your heart meter
Master the Hallucination Tunic
Call the developer from in-game
Get the "Perfect" ending
Save Lance
Save the Elder
Defeat Delvin without killing him
Defeat the Chairman without killing him
Kill a Whirligig
Defeat a boss without killing it
Get the Binoculars
Double your money in a single trade at the bank
Access a dungeon without defeating the boss in the dungeon before it
Confuse an NPC by naming yourself Lance
Beat the "Daily Seed" challenge
Melt ice before you obtain the lighter
Play a challenge
Get the "Sacrifice" ending
Bring powered-up Henrietta to the fight with Delvin
Cross the world wrap
Empower Henrietta
Do a lightning attack with the Tungsten Sword
Uncover the whole overworld map
Get the Patent
Get the Error Log
Get the Beta Cup
Drop a beer potion on yourself
Find a tomb under a gravestone
Get the IOU
Get the Book of Changes
Earn Paige's affections
Play Tombs & Tentacles
Get the Police Report
Unlock Paige as a companion
Do a spin attack with the Damascus Katana
Order a pizza
Unlock Shadow Lenna
Drop a hallucination potion on yourself
Kill a boss for the first time
Play local co-op with a friend
Find a cave within a cave
Blow up a rock before you obtain the bombs
Use a potion to skip Lance's death cutscene
Get one of every item
Get the "Catastrophe" ending
Beat the "1 Dungeon" challenge
Beat the "All Dungeons" challenge
Beat the "3 Hearts" challenge
Beat the "0 Hearts" challenge
Beat the "Arsonist" challenge
Beat the "Bomber" challenge
Beat the "Sniper" challenge
Beat the "I AM ERROR" challenge
Beat the "Reflex Mode" challenge