Stacking the same effect

[Dalebert]

I know I've read that effects of the same name don't stack. You take the more powerful one and apply that. Does anyone know where in the RAW this is discussed?

This came up last night where there were two gibbering mouthers and the DM made us save twice. I brought this rule up but some said it wasn't stacking to apply two saves when the effect was only once. My point is that applying two saves for the same effect IS stacking the effect.

Another case brought up was what if you're in two fireballs simultaneously. But according to the stacking rules, I don't think you would apply both simultaneous fireballs; only the stronger of the two.

[Kadesh]

Your DM is correct. If you start your turn within Gibbering Mouther A's Aura, and Gibbering Mouther B's aura, you must take the test the test for both.

This is specifically different from something like Meteor Swarm which deals damage ifcyou are within its AoE, even if the different AoE's overlap, they don't force additional saves.

Each one might be different, there is no specific rule. RtFM, or if you're playing, just play, trust your DM, and let him know if you're not having fun as a result of your DM having multiple effects essentially forcing you to failure.

[Dalebert]

I found the rule I was thinking of but it's only referring to spells. I thought there was a rule for the same of any same-name effect but maybe not.

[Unoriginal]

"No stacking effects" is not the same thing as "not getting targeted by the same effect from two sources"

For example, two casters couldn't both cast Reduce on a Medium PC to make them Tiny. However, if a PC gets targeted by two Reduce spells, the PC would need to roll the saving throws for both spells and beat the DCs in order to avoid the effects.

For the mouthers, each pf the Gibbering abilities targets the people in the radius separately, on their turn. It means you get hit by the effect once, it's resolved, then the other. However, the effects do not stack: if you are affected by one of them, you are not by the other. You just have to pass both saves.


It is impossible to be hit by two Fireball perfectly simultaneously in 5e, but one after another is perfectly possible.

[Lunali]

To be clear, which effect are you talking about? IMO the aberrant ground effect should only take one save while the gibbering effect should hit as many times as there are mouthers in range. That said, once you fail the gibbering effect, only one should affect you.

[Dalebert]

It is impossible to be hit by two Fireball perfectly simultaneously in 5e, but one after another is perfectly possible.

It's rare but not impossible. They could ready based on the same trigger. A friend has even seen it occur because they were waiting fro a hidden position for enemies to all move into an area to be affected.

Anyway, I have already conceded that the rule I was thinking of is only for spells.

[Mellack]

It's rare but not impossible. They could ready based on the same trigger. A friend has even seen it occur because they were waiting fro a hidden position for enemies to all move into an area to be affected.

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If you have two readied for the same trigger then it is now up to the DM if they want simultaneous or not. It is not listed in the rules what happens in that event, but I would think most would go by initiative order instead. I know my group does and Crawford said that is what he would do. So for some tables it is impossible, but interesting thought.

[lperkins2]

If you have two readied for the same trigger then it is now up to the DM if they want simultaneous or not. It is not listed in the rules what happens in that event, but I would think most would go by initiative order instead. I know my group does and Crawford said that is what he would do. So for some tables it is impossible, but interesting thought.

GoW would also let you detonate 2 spells simultaneously, without the benefit of initiative order to resolve them. That said, fireball has a duration of instantaneous, so both spells will still affect the target. Note that the spell stacking rules are for the same spell, with overlapping durations.

Also note that the stacking rules suppress rather than stop the less powerful spells. Consider if two spellcasters cast Magic Weapon, one at level 5 and one at level 2. The targeted weapon will count as a +2 weapon (from the level 5 slot) until concentration is broken or the duration expires, at which point it will count as a +1 weapon (from the level 2 slot), unless the weaker spell has expired or been lost. If that were a hostile effect, with a save, having you roll the save against the second spell would still make sense, since it determines what happens when the first copy of the spell expires.

This has interesting implications for spells like polymorph, where it's up to the GM to determine which invocation of it is 'the most potent effect'. Personally, I go with whichever one was cast from a higher slot, or whichever has the longer duration if the slots are equal.

[Zalabim]

You can find the rule in the DMG, I believe. It was added in errata, so you can just go to the DMG errata and find it there. The rule is:

CHAPTER 8
Combining Game Effects (p. 252). This is a new subsection at the end of the "Combat" section:

Different game features can affect a target at the same time. But when two or more game features have the same name, only the effects of one of them --the most potent one-- apply while the duration of the effects overlap. For example, if a target is ignited by a fire elemental's Fire Form trait, the ongoing fire damage doesn't increase if the burning target is subjected to that trait again. Game features include spells, class features, feats, racial traits, monster abilities, and magic items. See the related rule in the "Combining Magical Effects" section of chapter 10 in the Player's Handbook.