What level should this spell be?

[FrogReaver]

what is the dc if the constitution check?

 

[Worrgrendel]

what is the dc if the constitution check?

The target still remains the casters Spell Save DC. That's why the spells with "checks" instead of "saves" are more nasty. Don't get to add that proficiency bonus.

 

[FrogReaver]

The target still remains the casters Spell Save DC. That's why the spells with "checks" instead of "saves" are more nasty. Don't get to add that proficiency bonus.

Actually the spells I can think of that ask for a check tell what the check dc is.

 

[Worrgrendel]

Actually the spells I can think of that ask for a check tell what the check dc is.

Correct. And all of them (I'm very sure, but there are outliers like Counterspell and Dispel Magic that have their own rules but those are the casters making the check and not the target) state the DC is the Spell Save DC.

Wrathful Smite: Initial is a saving throw but then make a Wis check vs the Spell Save DC.

 

[FrogReaver]

Correct. And all of them (I'm very sure, but there are outliers like Counterspell and Dispel Magic that have their own rules but those are the casters making the check and not the target) state the DC is the Spell Save DC.

Wrathful Smite: Initial is a saving throw but then make a Wis check vs the Spell Save DC.

So how about letting the spell creator answer since he didn’t specify? I think that’s likely the case too but it’s not specified in his spell so no one but he can say 100% for sure

 

[Yunru]

Yeah, check vs spell save DC.
It's more dangerous against players than NPCs though, since NPCs tend to lack save proficiencies anyway.

 

[Krachek]

After the first miss, all other checks will be at disadvantage.
Also no proficiency, no legendary resistance, no magic resistance.
A spell is created to be used by the players, they will face it occasionally.
Level 5+

 

[77IM]

This is how I'd build this spell.

Drain Stamina
3rd-level necromancy
Casting time: 1 action
Range: 30 feet
Components: V, S, M (a preserved stirge proboscis)
Duration: Concentration, up to 1 minute

Chose a creature you can see within range. At the beginning of each of that creature's turns, it must make a Constitution save. On a failure, the creature gains one level of exhaustion. On a success, the spell ends.
​

Notes:
- 3rd level seems fine. This is not a really great spell for PCs to cast. It may have some utility against BBEGs. But it is absolutely terrifying in the hands of an NPC spellcaster, or worse, as a spell-like ability on multiple monsters.
- This should definitely be a Con save and not a Con check. Players expect to resist abilities like this by using Con saves, and build their characters accordingly, and making it a check instead doesn't really sound like much fun, nor make much sense.
- I shortened the range to 30 feet -- and then took out the part about "if you leave the range of the spell, it ends." This is considerably simpler in play. It does allow for some bad hit-and-run spellcasting, especially at higher levels, but I think the repeated saving throws should alleviate some of this.
- Preserved stirge proboscis was the best material I could come up with off the top of my head.

 

[FrogReaver]

After the first miss, all other checks will be at disadvantage.
Also no proficiency, no legendary resistance, no magic resistance.
A spell is created to be used by the players, they will face it occasionally.
Level 5+

Yep given that it’s a check and the first save makes it harder to save against and that it’s not possible to add proficiency bonus to the check I agree it needs a much higher level. Id say level 5 or 6 as written is a better fit. If it was a save I’d be willing to consider level 3 or 4.

 

[Blue]

Ah, that's an error. Originally it was a saving throw, but then failing once doesn't do anything, so I made it a check and forgot to change the later.

Also Hex and this both use Concentration?

A check is optional takes your action to do - I don't think you intend this to be forced action denial while they make a mandatory check.