How does the Sorcerer's Careful Spell Metamagic interact with the Earthquake spell?

Question

The earthquake spell is a bit unusual in that it calls for two saving throws:

[...] Each creature on the ground that is concentrating must make a Constitution saving throw. On a failed save, the creature's concentration is broken.

When you cast this spell and at the end of each turn you spend concentrating on it, each creature on the ground in the area must make a Dexterity saving throw. [...]

If the spell is cast and an affected creature is concentrating on a spell, they must make two saving throws. Meanwhile, the Careful Spell Metamagic states:

When you cast a spell that forces other creatures to make a saving throw, you can protect some of those creatures from the spell’s full force. To do so, you spend 1 sorcery point and choose a number of those creatures up to your Charisma modifier (minimum of one creature). A chosen creature automatically succeeds on its saving throw against the spell.

Which saving throw can the Sorcerer decide is automatically succeeds? Can they choose earthquake's specifically called for concentration saving throw?

Answer 1

This appears to be an oversight, but you can base your response on Heightened Spell

Earthquake is indeed unusual in that it calls for two saves on the same turn. Sleet Storm is also on the sorcerer list, and it similarly calls for saves against both losing concentration and falling prone at the same time. Unlike Earthquake, these saves don't happen on the turn you cast it, so if you think that Careful Spell applies only on the turn a spell is cast then it doesn't apply. Prismatic Spray, has a one-in-eight chance of hitting a target with two beams on the same turn it is cast, but this probably is still only one save.

With such a limited application, it is not surprising that Careful Spell neglected to consider a case in which more than one save would need to be made on the same turn. This appears to me to be a hole in the rules; you have found a case that is not covered by RAW.

Unless and until an errata appears to address this omission, perhaps our best rules guidance comes from another metamagic feature, Heightened Spell, which deals with the issue of multiple saves thusly (emphasis mine)

When you Cast a Spell that forces a creature to make a saving throw to resist its Effects, you can spend 3 sorcery points to give one target of the spell disadvantage on its first saving throw made against the spell.

My suggestion would be to allow Careful Spell to apply to only one kind of save made and the first of the two. Since the two saves occur simultaneously, I would use the timing rules in XGtE and allow the caster to choose which save to resolve first in Earthquake, and the creature affected to decide which save occurred first in Sleet Storm.

Answer 2

You can't use careful spell for the Earthquake spell

The rule for careful spell states:

When you cast a spell that forces other creatures to make a saving throw

The second "a" is the problem. It indicates a singular saving throw. Earthquake calls for multiple saving throws. As such, careful spell cannot be applied.