Suggestion
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.
OK, bolded part by me. What is reasonable? Therein lies the rub.
For example, we had just left a dungeon and were pretty beat up. Waiting outside for us were a bunch of cultists demanding we give them all of the treasure. I had one spell left, so I cast suggestion on him to tell his squad to step aside and let us pass unaccosted. The DM ruled they would have advantage, since they were fanatic cultists. He still failed.
so the DM ruled they still wouldn't follow the suggestion since failure in his mission would amount to suicide by his master, and thus, wouldn't be considered a reasonable request as described above.
My take: Well, if it had to be a reasonable request from their perspective anyway, then why have a spell for it? If it's reasonable, they'd do it anyway, right? You wouldn't even need a hard persuasion check, let alone a spell slot if it had to be reasonable from the get go.
Note: I'm not upset, or blaming the DM, or saying they weren't fair. Their game, their rules, and I"m OK with it. However, it's important to have these discussions beforehand, because as a sorcerer, I probably would have chosen a different spell to learn since spells known for sorcerers are far and few between. And I'm passing my lesson on to you
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