Here is the full list of all 38 Isbarah achievements.
Dash your father
Finish a boss without getting hit
Finish Abaddon using only the Dash ability and the Down key
Finish the first level in less than 3'48 without skipping the tutorial
Activate 3 railguns at the same time
Finish Jackal losing one heart during each Spell (Hard or 7th Hell mode)
Finish the Bird of Time without using either the Slow motion nor the Barrier power (Hard or 7th Hell mode)
Finish Nightmare without getting hit during his Custom phases
Finish chapter 5 without getting hit (Hard or 7th Hell mode)
Finish a level with the Ghost Bullet without getting hit
Stay in the air at least 1 minute standing only on Barriers and without getting hit
Finish a boss with all 3 challenges
Put your graze level to 50 in less than 7 seconds
Finish Death
Finish Death in Hard Mode without getting hit
Win at least 40k graze points during Abaddon's second Spell
Win at least 79k graze points during Wrath of Nature's first Spell
Finish all levels in Hard Mode
Finish a boss without using the Slow ability
Stop 30 bullets with a single Wall
Empty the Slow gauge 10 times in a single fight
Have a Game Over during the last Spell of a boss less than 2 seconds before its end
Have a Game Over during a Chase phase
Have a Game Over 3 times fighting the same boss during one gaming session
Have a Game Over 6 times fighting the same boss during one gaming session
Have a Game Over 9 times fighting the same boss during one gaming session
Come back after a 1-week absence
Finish 30 perfect Spells
Finish 60 perfect Spells
Finish 90 perfect Spells
Activate 200 Railguns
Finish Chapter 1 without using any Continue
Finish Chapter 2 without using any Continue
Finish Chapter 3 without using any Continue
Finish Chapter 4 without using any Continue
Finish Chapter 5 without using any Continue
Finish Chapter 6 without using any Continue
Get ranked 7 in all levels (126 score ranks to unlock)