Can twinned Vortex Warp proc Spirit Guardians damage if teleporting the Spirit Guardians carrier?

Question

So I've got Twinned Spell and Vortex Warp. I'm looking to abuse this in conjunction with hazard zone spells; one of particular interest is Spirit Guardians. What I want to do is take my ally from place X and enemy from place Y and place them near one another (both displaced to a new location) so that the enemy would proc Spirit Guardians and another hazard upon entering and again on their turn. Now, Spirit Guardians says:

An affected creature's speed is halved in the area, and when the creature enters the area for the first time on a turn or starts its turn there, it must make a Wisdom saving throw. On a failed save, the creature takes 3d8 radiant damage (if you are good or neutral) or 3d8 necrotic damage (if you are evil). On a successful save, the creature takes half as much damage.

Twinned Spell says:

When you cast a spell that targets only one creature and doesn’t have a range of self, you can spend a number of sorcery points equal to the spell’s level to target a second creature in range with the same spell (1 sorcery point if the spell is a cantrip).

Vortex Warp says:

You magically twist space around another creature you can see within range. The target must succeed on a Constitution saving throw (the target can choose to fail), or the target is teleported to an unoccupied space of your choice that you can see within range. The chosen space must be on a surface or in a liquid that can support the target without the target having to squeeze.

Last part of this ruling comes from Sage Advice Compendium, which says:

Our design intent for such spells is this: a creature enters the area of effect when the creature passes into it. Creating the area of effect on the creature or moving it onto the creature doesn’t count.

Far as I can tell, this is a unique situation in the sense that the hazard zone and creature are both moving simultaneously so previous precedent doesn't make this trivial. So, I guess the question is whether they're entering Spirit Guardians when Vortex Warped; does Twinned Vortex Warp occur simultaneously or progressively (if progressively, they're trivially entering) and if not, does the fact that the hazard zone move matter if they're also moving into it for the first time in the turn? By all my logic this should work but I'd like for others to weigh in here.

Answer 1

This depends on resolution order, by default the DM decides

As you state, the core of your question is if the transposed creature counts as entering the Spirit Guardians' area, when both it and the creature with Spirit Guardians are transported at the same time by Vortex Warp.

If the creature is entering the area, then it will have to save against damage. For example, if you just Vortex Warped the creature to a space next to your ally who has Spirit Guardians going without transporting your ally, then they clearly enter the pre-existing Sprit Guardians area. This is further supported by additional text in the Sage Advice Compendium answer:

Entering such an area of effect needn’t be voluntary, unless a spell says otherwise. You can, therefore, hurl a creature into the area with a spell like thunderwave. We consider that clever play, not an imbalance, so hurl away!

This also is cheaper than twinning Vortex Warp -- you just need a normal casting of Vortex Warp, and no sorcery points. So, it is not clear to me what the advantage would be to twin the spell and also transport the creature with Spirit Guardians. That approach seems to be just added cost and complication, without added benefit.

Teleporting both creatures

If you move both creatures by twinning Vortex Warp, than the effect will resolve simultaneously, as it is the same spell resolving on multiple targets. The game has no core rules how to handle competing simultaneous effects, so it will be up to the DM do order what happens first, as per p. 4 DMG "as a referee, the DM interprets the rules":

• If the transport of the Spirit Guardian creature resolved first, the Spirit Guardians area is there and is being entered as in the case above, and the vicitm will have to save against damage

• If the transport of the victim is resolved first, than the Spirit Guadian is put onto the victim afterwards, and they will not need to save against damage

There is an optional rule from Xanathar's Guide to Everything (p.77) for resolving simultaneous effects that states:

In rare cases, effects can happen at the same time, especially at the start or end of a creature's turn. If two or more things happen at the same time on a character or monster's turn, the person at the game table - whether player or DM - who controls that creature decides the order in which those things happen.

If your DM uses this rule, and it is your turn (which is likely if you are casting spells), you get to decide the order in which the effects happen, and you can elect to have the creature with Spirit Guardians arrive first, so that your victim will need to make a saving throw against damage.