To what level is it worth doing this debuff with your standard action?

[SangoProduction]

If you've got a spell that can exhaust on a failed save (and still fatigue on a successful save), is there going to be a point where spending your action on doing that is not worthwhile?

In one of my recent questions, I asked if 1d3 (average 2) negative levels was worth using at level 11. General response was no. It simply doesn't do enough, despite an average of -2 to all rolls, and potential fringe benefit of debuffing caster levels, and knocking out their most dangerous spells.

Exhaustion is a -3 to most attack rolls, and -3 to AC and reflex saves in the large majority of cases. And of course, the half speed thing, but who cares about that? Meanwhile fatigue is only a -1 to those things.

When does this stop being worth doing? Or how many targets must you hit with each cast to make it worth doing?

[Kurald Galain]

If you've got a spell that can exhaust on a failed save (and still fatigue on a successful save), is there going to be a point where spending your action on doing that is not worthwhile?
Of course there is; and that point is when you can cast better spells (and bear in mind that numerous spells are overleveled).

Generally speaking, a good first-level spell will debuff a single target (e.g. Grease, Ray of Enfeeblement, Blade Lash).
A good second-level spell will disable a single target entirely, but with targeting restrictions (e.g. Hold Person, Command Undead) or debuff an area (e.g. Web, Stinking Cloud).
A good third-level spell will debuff enemies only (e.g. Slow), or debuff with no saving throw (e.g. Sleet Storm, Inflict Pain).
A good fourth-level spell "takes over" an enemy (e.g. Charm Monster) or disable a group of enemies (e.g. Fear, Confusion).
And a good fifth-level spell straight out terminates an enemy (e.g. Slay Living, Baleful Polymorph).

So your spell fits in with first-level spells and would be less worthwhile when you can regularly cast good second-level spells.

[Gnaeus]

It’s better than Kurald suggests because your spell is a limited target no save disabler. That is, it shuts down any monster that relies on charge attacks on a failed or succeeded save. As such, it is worth keeping until higher levels (although better as a scroll since you don’t care if they make their save).

Outside that limited threshold, it depends on what else you were going to do with that action and the cost of the exhaustion spell. Put it on a ranger and it may see use. On a wizard, only if it’s a low level slot. Make it a witch hex and it may be worth taking, and using on rounds when you are saving resources.

Edit: it would also be a handy spell for capturing people. They can’t run away and their attacks are nerfed. I could see use by law enforcement or in bar fights where you don’t want a pile of corpses.

[Elkad]

I'm with Gnaeus. It becomes situational as your enemies level up.

If you are kiting, it's pretty valuable (especially if it has a good range). Your enemy will slow down and you pincushion him from range.

If you are a high AC melee type (or supporting one), that -3 to hit might drop the enemy's damage output by 50% or more, so it's still very useful.

If you lack defenses and just rely on damage output, it's not going to do much.

It's not worth using on a caster of course.

And of course if the encounter is a horde of mooks, a penalty to one of them isn't worth the action at all. Throw a fireball or whirlwind attack.

[Kurald Galain]

It’s better than Kurald suggests because your spell is a limited target no save disabler.
Forcing an enemy to do something else besides charging is a debuff, not a disable. Disabling means forcing him to do nothing.

[Gnaeus]

Forcing an enemy to do something else besides charging is a debuff, not a disable. Disabling means forcing him to do nothing.

Shooting a ray of enfeeblement is a debuff. It gives the target -2/-2. Forcing a charge build to not charge is a no save just lose.