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.

  • \$\begingroup\$ If the damage does not stack, then you should considering adding an additional aspect to the question. "What happens when you case Vitriolic Sphere on the same targets on your text turn?" Does the new, higher damage effect override the attack on the previous turn? \$\endgroup\$ Jan 24, 2017 at 16:54
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    \$\begingroup\$ @LinoFrankCiaralli, I am questioning if the "most potent effect" rule even applies here \$\endgroup\$
    – András
    Jan 24, 2017 at 17:58
  • \$\begingroup\$ Ah seen, this is an instantaneous effect, not an ongoing one. \$\endgroup\$ Jan 25, 2017 at 3:07
  • \$\begingroup\$ Fair enough. I'll buy that. \$\endgroup\$ Jan 25, 2017 at 8:45

2 Answers 2


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.

  • \$\begingroup\$ 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. \$\endgroup\$
    – T. Sar
    Jan 27, 2017 at 8:55

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.

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    \$\begingroup\$ 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. \$\endgroup\$ Jan 24, 2017 at 16:36
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    \$\begingroup\$ @JohnGrabanski "Effects of the same spell cast multiple times do not stack" still applies regardless of how many casters are involved. \$\endgroup\$ Jan 24, 2017 at 18:01
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    \$\begingroup\$ @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. \$\endgroup\$ Jan 24, 2017 at 18:04
  • \$\begingroup\$ @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"). \$\endgroup\$ Jan 24, 2017 at 18:20
  • \$\begingroup\$ @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. \$\endgroup\$
    – T. Sar
    Jan 27, 2017 at 8:53

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