Just curious if any DMs out there allow a player to walk up to an NPC that is sleeping and just slit their throat for a instant kill? Seems to me if we are thinking realistically and that NPC has been knocked out or put to sleep by a spell, they aren't defending themselves and it could easily be done. Thoughts? Comments?
Depends.
If he wanted to do this on Orcus who had prior been sleeped by the wizard, than no, regardless of how much sense it makes.