Chwinga from ToA are fun for Conjure Minor Elemental!

If you name CR 0 for the spell, the DM has no choice but to give you chwinga, since they're the only CR 0 elemental, so you're ensured to get them if you want them when you cast.

You get 8 chwinga, and give one to each party member to perch on the party's shoulders. The chwinga give each party member a charm from their 1/day Magical Gift (which the DM chooses), and then cast your choice of Resistance, Guidance, or Pass Without Trace continuously. If you have a smaller party, you can double or triple up chwinga on each person, with each chwinga casting a different one of these spells, so that each person has Guidance, Resistance, and Pass Without Trace. Alternatively, have all 8 chwinga riding on one person and casting Guidance or Resistance; since the rule for multiple instances of the same spell state that the bonuses don't stack but you can choose the highest bonus rolled, you're all but guaranteed a bonus of 4 every time for that person.

They can also be used for getting into small, otherwise hard to reach places, and for stealth missions, since they can cast Pass Without Trace on themselves, already have a very high Stealth, and can meld with surroundings if in a natural environment.

This seems a little OP, but consider it costs a 4th level spell slot, they have no way to deal damage, they only have 5 HP so die very easily, they vanish if your concentration on the spell is broken, and they can't carry much or speak any languages. The DM gets to pick the charm, and could just give everyone the same relatively lame charm, like darkvision.

But for an hour if you can keep them around, you've got 8 buddies.

"You choose one the following options for what appears:" CR 0 isn't an option, I'd run that by your GM before attempting to do so!

"Eight elementals of challenge rating 1/4 or lower."

It is technically an option, seeing as it qualifies by the "or lower" portion. However, it can end up being pretty busted. Special consideration should be made ahead of time as to whether it is allowed, or because of the abilities they have the amount of Chwinga summoned is lowered.

Or you could summon 8 mud mephits to have a 216 hp shield

Does the elemental have to be able to understand the language spoken by the conjurer? Or would the spell allow them to innately understand? If I conjure an azer, but I don't speak Ignan (or Primordial), is it just going to stand around confused, wondering how it got there and just do nothing?

Quote from TommyP365 >>

Does the elemental have to be able to understand the language spoken by the conjurer? Or would the spell allow them to innately understand? If I conjure an azer, but I don't speak Ignan (or Primordial), is it just going to stand around confused, wondering how it got there and just do nothing?

 
Since spells in 5e typically do only what they say all you have to worry about are these two lines:

“They obey any verbal commands that you issue to them.“

”If you don't issue any commands to them, they defend themselves from hostile creatures, but otherwise take no actions.”

Since there’s nothing about the caster sharing a language with them, you don’t need to. As far as the spell is concerned as long as the command is verbal the elemental will comply. Likewise, according to the spell, the only instance where they do nothing is in the absence of both verbal commands and hostile creatures. 

a quick search in the bestiary will show there are air elementals, fire elementals, earth elementals, and water elementals, though these are all CR 5 and beyond the bounds of this spell (they require Conjure Elementals). There are also numerous other elemental creatures of various CRs that qualify for both spells beyond the 4 Elementals 

"cr 1/4 or less"

with a 8th slot you can have 24 chwinga

Note that the spell has a casting time of 1 minute, unlike the other conjure spells.

I'm the DM and my player is pretty upset that it's got a 1 minute conjure time, making it pretty bad for the battle ground. What do you think the intent was to have this as markedly different than the other conjure spells?

Since this spell lasts one hour, it's a good spell to Cat ahead of time, when you have a little time to plan. Since elementals have more inherent uses than that which a Conjure Animals would make(such as a Chwinga's ability to cast Pass Without Trave among other things). It's more ability utility i imagine, or being prepared for a few situations.

TYPO IN SPELL TEXT.  This typo is in the PHB as well.

"You choose one _OF_ the following options...."

Quote from ButterBiscuit99 >>

TYPO IN SPELL TEXT.  This typo is in the PHB as well.

"You choose one _OF_ the following options...."

 oof

Not oof, of

Summon four magma mephits to harass enemies by casting heat metal on their weapons/armor, they then fly out of range and you never even revealed yourself to the enemy.

Not that any DM would allow this, but since their CR is exactly the same, you could totally summon the summoner variants of the Mephits and use their abilities to summon even more Mephits into battle. With a 25% success rate, that should be about 2d4 additional Mephits on average assuming you use one of the 1/4th challenge rating ones! Plus they can be summoned up to 60ft away from the summoner, so the ones that successfully pull it off can hang back while the failures charge into battle. The end result, a tidal wave of tiny minions that won't do too much damage, but can whittle enemies down while soaking up a TON of punishment. Just watch out for AoE attacks like breath weapons and fireballs.

This spell got a little bit more powerful with Art Elemental Mascots from Strixhaven. They can charm a creature and they even have a Death Burst ability that blinds creatures for a minute within 5ft of them when they die.

theoretically up to 1080 hp meat shield. Each mephit is capable of summoning 4 more mephits