I had lab maniac out on the field with 2 cards left in my deck. I used my wizards spellbook to draw 2 cards and lab maniac triggered but it still made me lose. I was against an Ashiok if that matters
For Lab Maniac to work, it needs to be played on your second to last turn.
I just had the EXACT same thing happen in a game also against Ashiok. 3 cards left in deck, play Laboratory Maniac, use artifact to draw two cards. The trigger on maniac procs as the message pops up, then get defeat message.
It is definitely due to Ashiok nightmares.