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