In my game, we have a Wild Magic sorcerer in the party. During a recent combat, they rolled on the Wild Magic table and got the effect:
95-96: You and all creatures within 30 feet of you gain vulnerability to piercing damage for the next minute.
So far, so good. The whole combat encounter was very close together, so this affected everybody. Then, they used Tides of Chaos again, and had to roll on the Wild Magic table once more, and got:
31-32: You are transported to the Astral Plane until the end of your next turn, after which time you return to the space you previously occupied or the nearest unoccupied space if that space is occupied.
While they were gone, one of the enemies attacked with piercing damage. Are we all still considered vulnerable to piercing damage whilst the sorcerer is no longer within 30 feet?
Best Answer
I would say the effect sticks to the creatures who were near the Sorcerer at the time the vulnerability was tossed out, and doesn't travel with them. So in your specific case, even though the Sorcerer isn't around, you'll still take double piercing damage. This also means that the Sorcerer running up to an enemy who wasn't effected will not make them vulnerable either.
The reason I'm saying this is because of the wording of this spell is fairly consistent with many other spells and effects, and is in the general form: [target] [effect] [duration].
Target here is "you and anyone within 30ft of you", the effect is "gains vulnerability to Piercing" and the duration is "the next minute".
If the idea was that this effect would travel with the Sorcerer, it'd more likely be worded as something that only targets you, but has an effect on anyone near you.
I might expect a wording more like "You are affected by [fancy name]. While affected by [fancy name], you and anyone within 30ft of you are Vulnerable to Piercing damage. This effect lasts for one minute.".
Alternatively, I would have expected the word "aura" to appear within the description of the ability, which does exist with Paladin auras for example.
"For one minute, you radiate out a 30ft aura that gives all creatures within it (including you) Vulnerability to Piercing damage".
You can see the same kinds of descriptions in spells like Antimagic field ("Until the spell ends, the Sphere moves with you, centered on you.") or Spirit guardians ("They flit around you to a distance of 15 feet for the Duration.").
Lacking either of these makes me think it just defaults to what usually happens with effect descriptions; you decide targets at the moment of "casting" and then it hits only those targets for the duration.