You suggest a course of activity (limited to a sentence or two) and magically influence a creature you can see within range that can hear and understand you. Creatures that can't be charmed are immune to this effect. The suggestion must be worded in such a manner as to make the course of action sound reasonable. Asking the creature to stab itself, throw itself onto a spear, immolate itself, or do some other obviously harmful act ends the spell.
The target must make a Wisdom saving throw. On a failed save, it pursues the course of action you described to the best of its ability. The suggested course of action can continue for the entire duration. If the suggested activity can be completed in a shorter time, the spell ends when the subject finishes what it was asked to do.
You can also specify conditions that will trigger a special activity during the duration. For example, you might suggest that a knight give her warhorse to the first beggar she meets. If the condition isn't met before the spell expires, the activity isn't performed.
If you or any of your companions damage the target, the spell ends.
* - (a snake's tongue and either a bit of honeycomb or a drop of sweet oil)
https://twitter.com/JeremyECrawford/status/663432885475545089
Per Jeremy Crawford, the spell doesn't cause someone to be charmed, so this shouldn't have the damage/effect of Charmed.
So elves don't get advantage on their saves against it?
Based on Jeremy Crawford's tweet, they do not. Creatures with charm immunity, however, are still safe :)
So this is the situation. Two ogres were arguing over gold so i used suggestion on one saying "he's going to try and kill you and take the gold, kill him first" I figured they were already arguing and they're ogres so it wouldn't be out of the norm for one to attack the other over gold but the spell saying an obviously harmful act ends the spell. So should the suggestion have stuck?
This spell does have the charmed effect and specifically states that creatures immune to charm are immune to this spell. The target creature is effectively subject to the charmed condition, though the governing conditions make it a narrow definition of charmed.
Where in the spell does it say it gives the charmed effect?
yes it should have stuck because by wording the harmful act only talks about the spell not taking effect if you ask it to hurt itself you asked it to kill something which isnt asking itself to harm itself.
So the easiest way out is for the NPC to state “that doesn’t sound very reasonable”.
Lethain
In your orge scenario I would rule that the spell would have succeeded in causing a fight to break due to the context referring all to self-harm and also since they were already arguing.
is there a save for each turn or one save till the act is completed?
It doesn't specifically say that a save can be repeated, only that the course of action can continue for the entire duration. I ruled it that way when I had a wizard cast this on the party barbarian, who failed of course, and had him attack an ally. Until the wizard lost concentration, he had an extra beef cake to attack the party.
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The examples the spell gives are obviously harmful to yourself (stabbing yourself etc.). Harming others that you would reasonably harm anyway is well within the limits of the spell. I would say that with your suggested order, the ogre would attack his friend once, and then potentially stop, but his "friend" would probably attack him back ofc. ;P
Asking a random passerby "why don't you just push that guard into the river as a prank" is a perfectly reasonable suggestion for instance, even if the river is toxic and the guard is wearing fullplate.
Can you have the target guard something with its life? e.g. "Fight anyone who tries to get in this door; don't let them in, or die trying."
I would argue that "guard with it's life" is evidently a course of action that would be considered harmful to itself. You could say "Guard this door and stop anyone who tries to enter it"
My favorite thing about this spell: No knowledge that you have magically manipulated them. If it's truly a "reasonable" suggestion then they will tell themselves they were just following reason, and self-justify any weird parts of it. Even if their behavior was effectively crazy, they won't know why they listened to you, unlike Charm Person where they understand inherently they were charmed. That said they might remember your Verbal/Material behavior in casting the spell, and put the pieces together later. Making sure your "suggestion" makes sense if they successfully save seems valuable in most situations. If it's too obvious the likelihood that they put it all together and know you were manipulating them would go up. Ideally you'd usually want to be able to keep trying to get what you want with persuasion/deception even if the wisdom save kills your suggestion.
My question for myself is whether I need to keep both this and Charm Person for my mental-manipulation GOO Warlock. In most cases Suggestion is a direct upgrade, and IMO I could craft "suggestions" that get what I want easier than doing a ton of persuasion rolls with a charmed person. That said, it sounds like DMs can really ruin the power of suggestion, and the simple mechanics of Charm Person (especially being able to charm several at once) could come in handy. For a Warlock who can swap spells each level, it's hard to justify keeping Charm Person+Suggestion when I could have Detect Thoughts+Suggestion working together (of course I could have all three, but I'd be seriously overloading myself with social spells).
This spell doesn’t require concentration, so if you fail the first save, that is it. You are stuck for the duration, or until the action is complete.
It has the concentration symbol next to the duration. I believe it requires concentration.
Imagine a guard knowing suggestion and using it to tell criminals "Stop right there! You violated the law!"
Creatures with charm immunity: Your jedi mind tricks don't work on me