What constitutes a suicidal command?

Question

The succubus has an ability called Charm. Its description states that a suicidal command results in the charmed creature repeating the saving throw to resist the command:

If the target suffers any harm or receives a suicidal command, it can repeat the saving throw, ending the effect on a success.

But what is considered a suicidal command? Is it only a command that kills you 100% of the time? Is it any command that damages you? How about indirect damage?

Jumping off a 1000-foot cliff sounds pretty suicidal, but at level 20, most characters could survive that easily, since falling damage caps at 20d6. There is almost nothing in the game that could consistently one-shot a level 20 character, so does that mean nothing is considered suicidal to them at full health?

I have considered maybe a percentage damage. 50% of max health could be considered suicidal, but the problem is that any set percentage would be arbitrary, and that sounds very much like a hidden rule, which D&D tries to avoid. Any damage could mean lethal consequences if you only have 6 HP. Every hit point is extremely valuable, so unless the percentage shifts according to max HP and other weird stuff, this version wouldn't really make sense.

Maybe if it does kill you, it is considered suicidal? The problem is you cannot know whether something kills you until you roll the dice, and you cannot roll the dice until it is your turn, since plenty of stuff could happen in between getting the command during the succubus' turn and yours. And since a successful save means you resist the charm, and the saving throw is supposed to happen when you receive the command, this isn't really possible.

The best option I can find is counting all damage you do to yourself through environment or actions as "suicidal".

Are there any official rules on how a "suicidal command" is defined?

Answer 1

Ultimately, it's up to your DM, but you should have a pretty good idea of what it means

It's up to your DM to decide if the command is suicidal or not. A plain English reading of "suicidal" is "[something that is] likely to have a disastrously damaging effect on oneself or one's interests."

Jumping off a 1000ft cliff sounds pretty suicidal, regardless of whether or not you will actually die. Therefore it's a suicidal command.

Any damage could mean lethal consequences if you only have 6 HP, so any command that could lead to you taking 6 or more points of damage would be suicidal.

There is no hard or fast rule, but when issuing a command you should consider whether the character considers there to be a possibility of death resulting from the command. If so, that's a good indicator that the command is suicidal.

Remember to enjoy the game

Finding loopholes that allow you to kill your players may well be something that a succubus would want to do, commanding people to do compromising things to give an opportunity to slay the target. But, don't go too overboard. The DM has a lot of power, and also a lot of responsibility. Making your players feel powerless should probably be done sparingly.

Answer 2

I would say anything that the dominated character is likely to think would kill them. It doesn't have to be an accurate assessment. A cowardly goblin might get a new save if you order them to kill a commoner who succeeded on an intimidation check, even though the fight would almost certainly go in the goblin's favor, because the goblin thinks the commoner is stronger than he actually is. Conversely, a lycanthrope wouldn't get a new save to attack the martial-looking guy with a hidden silver dagger until he actually saw the dagger, because he's expecting to be immune to the guy's attacks. Even then, he might figure he can survive a few hits from silver and still take the guy out.

If they've survived similar falls in the past, or have some kind of fall-mitigation ability that trivializes the fall (flight, feather fall, rage, etc), they won't get a new save to jump off of something. (Unless you specifically order them not to use any fall mitigation abilities - that would trigger a save if they'd think those would be necessary to survive the fall.)

If you're using it against players, I'd say that you outright ask them: would your character think they're going to die if they do X? If they answer yes, tell them to repeat the save. Of course this only works if you trust your players to be honest.