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