D&D 5E NPCs using spells with a HP threshold (like sleep). How much do you metagame?

[Harzel]

I'm running Hidden Shrine from TftYP today (SPOILERS!).

There is a monster with a sleep spell in it. It's a fight that is probably best avoided (you really have to go out of your way to meet the creature...by the time we get here, the PCs are likely low on resources and should be just hoping to escape).

But it makes me wonder...how much do DM's metagame spells that have a hp threshold and no save like sleep? Do you have the NPC cast them early expecting to weed out any weak foes? Do you have them wait until some of the PCs are weakened enough to be easily affected? Do you maybe allow more intelligent NPCs to "know" when such spells will work and use them to best tactical advantage?

I'm not quite sure of the exact NPC behavior you have in mind, but for me, except in very unusual circumstances an NPC spell caster knows how their spells work. They don't know about hit points, per se, but would know qualitatively how sleep works:

• it affects weaker creatures in preference to stronger creatures;
• it affects more creatures when cast on weaker creatures;
• it interacts with a strong but critically wounded creature in much the same way it would with an unscathed weaker creature.
• In addition, they probably know that creatures can be roused from the effects fairly simply.

Whether the NPC uses it to best tactical advantage depends on how good a tactician the NPC is, which is something I prefer to give a bit of advance thought to, although some may be comfortable deciding that on the fly.

In this case the NPC has a 14 int...not super smart. He is a "god" of sorts and will probably assume any interlopers are weakling humans so I think he is likely to open with sleep with a plan on playing with his new found toys at his whim.

INT 14 is substantially above average for humans. I'm not familiar with the module or the NPC, but all other things being unexceptional, I would expect him to wait until he believes* the spell would down at least 2 opponents, or he is out of better spell options. If he knows that he is facing multiple opponents and has access to AoE damage, I would expect him to open with that instead.

Playing him as arrogant enough to be foolish is ok, I guess. But how did he get to where he is without being at least a little bit savvy?

*Whether he makes that judgement correctly would likely (for me) be a matter of some uncertainty.

 

[Uller]

INT 14 is substantially above average for humans. I'm not familiar with the module or the NPC, but all other things being unexceptional, I would expect him to wait until he believes* the spell would down at least 2 opponents, or he is out of better spell options. If he knows that he is facing multiple opponents and has access to AoE damage, I would expect him to open with that instead.

Playing him as arrogant enough to be foolish is ok, I guess. But how did he get to where he is without being at least a little bit savvy?

*Whether he makes that judgement correctly would likely (for me) be a matter of some uncertainty.

I agree. It will be a guess but an educated one.

We got through a substantial portion of the adventure this evening. The party is bruised and battered (between half and full HP, everyone is out of HD, two Healing Potions left, a handful of spell slots.

The NPC is an Oni. His abode is in an ancient dungeon complex loaded with traps and monsters. The adventure doesn't say but to me, he was probably treated as a god and brought sacrifices to torment and flay alive before eating them. It is very difficult for more than one PC to get to him at a time (like I said...hopefully they just avoid him). Likely I'll have him look at whoever his victim is and size him up. If he's looking ragged and worn down already, the Oni will sleep him, tie him up and torment him. If others manage to get to him he's got a fear spell. If whoever gets to him seems healthy, he might wear him down some first before sleep.

I do use the "bloodied" condition from 4e for my players (actually, we are playing on Roll20 and I display the HP bar too...so what's good for them is good for the monsters. So I'll probably just key off of that. Really the question is just more academic since I am hoping they just avoid this guy.

It's a fun adventure...it's like a Tomb of Horrors, light...They stirred up a Will o' Wisp that keeps following them and trying to murder downed PCs (autocrit + 2 failed death saves!). Two of them got down to just 1 death save remaining tonight...