Here is the full list of all 35 Good Night, Knight achievements.
Die for the first time.
Get a x2 experience multiplier.
Get a x3 experience multiplier.
Get a x4 experience multiplier.
Get a x5 experience multiplier.
Kill the MotherSkell.
Extract two monsters at once with the extraction sword.
Extract 4 monsters with the same extraction portal.
Extract a high priority Miniskell.
Extract a high priority Ghallo.
Extract a high priority Stabman.
Extract a high priority Bigskell.
Extract a high priority Firesnake.
Extract a high priority Spider.
Extract a high priority Decayed.
Extract a high priority Spikyboy.
Extract a high priority Fallen Knight.
Extract a high priority Twohead.
Extract a high priority Haunter.
Extract a high priority Siren.
Extract a high priority Redwasp.
Extract a high priority Pouncer.
Extract a high priority Seeker.
Extract a high priority Croaksu.
Extract a high priority The Cage.
Extract a high priority Bedlusk.
Kill the Venus Knight-Trap.
Extract a high priority Barkarmor.
Extract a high priority Shrubber.
Extract a high priority Eagle Knight.
Extract a high priority Sage Knight.
Extract a high priority Protector.
Extract a high priority Penitent.
Extract a high priority Tick.