Here is the full list of all 55 Phantasmal achievements.
Killed a Starver
Killed a group of spiders
Fifty Starvers and still counting!
Opened five locked cases
Opened fifty locked cases
Completed Level One
Completed Level Two
Completed Level Three
Completed Level Four
Completed Level Five
Twenty Five starvers!
Killed a junkie
Killed fifty junkies
Killed a hundred junkies
Killed a spitter
Killed ten spitters
Killed thirty spitters
Killed a creepy kid!
Killed five creepy kid!
Killed twenty creepy kids!
Killed a shadowman
Killed five shadowmen
Killed ten shadowmen
Killed a shadowhound
Killed three shadowhounds
Killed eight shadowhounds
Completed Thread One
Completed Thread Two
Completed Thread Three
Completed Thread Four
Found all story thread one's notes!
Found all story thread two's notes!
Found all story thread three's notes!
Found all story thread four's notes!
Fully upgraded flares.
Fully upgraded health.
Fully upgraded keys.
Fully upgraded sneak.
Fully upgraded sanity.
Fully upgraded sprint.
Fully upgraded pistol ammo.
Found five secret rooms
Found fifty secret rooms