Here is the full list of all 17 Last Year: The Nightmare achievements.
Abandon a trapped friend, and let them deal with the Killer alone...
As a Killer, use an Execution move on a downed Survivor.
As a Killer, take out a full team of Survivors during the escape phase.
As a Killer, kill all the Survivors without more than 2 minutes between each kill, and without dying.
As a Giant, throw a Survivor off of the top floor of the Belltower.
As a Killer, gas an unsuspecting survivor by rigging a Scavenge spot in Predator mode.
Get killed by someone who already has this Achievement.
Be the only survivor to finish a match alive.
Take out both a Killer and a fellow Survivor with a single Thermos Bomb.
Kill yourself.
Spend 40 Scrap in a single match.
Barricade a trap door that you have previously fallen into during the same match.
Put two Nail Gun Turrets next to each other and let them fight it out.
Be the first Survivor to finish a match in which all Survivors also finish the match.
Save a Survivor being grabbed by the Strangler by hitting him.
Finish a match alive as a survivor.
Go from one Survivor alive to having all Survivors alive in one game.