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Vitriolic Sphere:

On a failed save, a creature takes 10d4 acid damage and 5d4 acid damage at the end of its next turn. On a successful save, a creature takes half the initial damage and no damage at the end of its next turn.

If a 7th level Wizard/ 2nd level Fighter uses his Action Surge to cast this spell twice on the same target, and it fails both saving throws, how much damage does it take at the end of its next turn?

What if two casters use Ready to cast the spell at exactly the same time? In this case both the initial and the secondary damage comes at the instant.

András
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2 Answers2

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Both spells do their normal damage

The relevant rule (PHB p.205) is:

Combining Magical Effects

The effects of different spells add together while the durations of those spells overlap. The effects of the same spell cast multiple times don't combine, however.

In context, the same spells do not combine while the durations of those spells overlap. Vitriolic Sphere has a duration of Instantaneous - multiple castings can never overlap in their duration even if their effects do overlap.

Community
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Dale M
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  • It's worth to note that what the spells do is to create a delayed amount of damage, in the same manner that Delayed Fireball did back then on D&D 3.X. Your answer is pretty much on point. – T. Sar Jan 27 '17 at 08:55
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Effects of the same spell cast multiple times do not stack. The instantaneous damage would both happen, but only one of them would do damage the next turn.

user3294068
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    Would this change if it was from 2 Casters? Since it's not ongoing damage, but an effect that happens on a failed save. I would initially think they would both apply. – John Grabanski Jan 24 '17 at 16:36
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    @JohnGrabanski "Effects of the same spell cast multiple times do not stack" still applies regardless of how many casters are involved. – LegendaryDude Jan 24 '17 at 18:01
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    @LegendaryDude I'm curious about this because the duration of Virtrolic Sphere is Instantaneous, so the duration of the spells do not overlap. Which I feel this might be a special case. – John Grabanski Jan 24 '17 at 18:04
  • @JohnGrabanski The duration of the spell is instantaneous, but the effects also seem to have a duration (specifically, until "the end of [the target's] next turn"). – LegendaryDude Jan 24 '17 at 18:20
  • @LegendaryDude The spell doesn't stack but the effects do, since the spell is very much over already when the end of the next turn hits. The spell creates a delayed blast of damage, and damage always stack. Think of this in terms of Dealayed Fireball from D&D 3.5. – T. Sar Jan 27 '17 at 08:53