Here is the full list of all 36 Gloom achievements.
Ten wins in a row
Three wins in a row
Leo's blades and both eyes simultaneously
Win in less than 8 minutes and 30 seconds
Must be routine at this point
Well that's just sadistic
Win in less than 12 minutes
The book in all its glory
A grander existence
An embryo of the cosmic way
You've got the hang of it
To retrieve what was once lost
Most renowned of them all
He had it coming
A place for gloom
No more dreaming, no more nightmares
A pillar of demented faith
A pillar of demented art
A place for expression and madness
A place for ascension
All for one
A mirror of null existence
An orphan of spite
A ghastly tide of salvation
One-of-a-kind weapon
An instrument of ascension
A place for silence and emptiness
A narrator of nightmares
Resilience is a virtue
A place for the shunned and forgotten
An agent of secrecy
A false prophet of ill omens
A fallen deity of envy
A place for the lost and demented
An embodiment of deific anger
You perished in a dream