Here is the full list of all 21 Pesadelo - there are Regressão achievements.
First entrance in Black Oak Cemitery
This Archievement is not for you. Thanks Oblivion.
First entrance in the Cave
This is just the beginning. Died 5 times
You like papers. Pick up 10 documents
"listening to a radio" you heard all radiologs
You get all documents
Make the Orchid Soul poison
Burning all 4 poisonous flowers
Found the code, you know multiply!
First entrance in the Eucaliptal
Found the mausoleum key
You found all the literature of Cordel
You burned the 4 treasures
You play the Melody of The Pain
You won the cursed priest
Break all the chalks and pens
You found the secret door of the church!
Makes 5 Arnica's Drink
You finished the Pesadelo – Regressão