Use Magic Missile to determine whether a statue is an Object or a Creature?(!)

[iserith]

It may be harsh, but I think it's totally fair.

If the caster doesn't want to waste a slot, they can make a better decision than blindly throwing any old spell at the problem.

I'll take "harsh but fair" over "unfair" any day of the week.

 

[Sword of Spirit]

Here’s my take. I don’t allow magic missile to identify non-creatures because I do not believe that is part of the intended utility of the spell. Same with any other targeted spell that only affects creatures. So what happens? The spell hits (or attempts to hit if an attack roll is required) the target. If the target is invalid for the spell, there is no effect. (Magic missile isn’t self-directed, it is sight directed. It hits something you can see.) I encourage anyone to consider this method of adjudication.

In the case of damaging effects that probably should do something (like ray of frost) I would house rule it that it does do a bit, just not enough to be combat relevant. Sure, you can chill your beverage with ray of frost, but no you can’t freeze something and then break it.

 

[Dausuul]

For what it's worth, I think that the "official ruling" of expending a spell slot is a bit harsh.

You can do it with a cantrip just as easily. Most attack cantrips specify creatures as targets.

 

[iserith]

You can do it with a cantrip just as easily. Most attack cantrips specify creatures as targets.

Sure, I think my concerns about the harshness of that rules clarification has to do with implementing it without the player's prior knowledge. I think any player who knows that is the ruling would reasonably choose a cantrip over "wasting" a spell slot.

 

[Satyrn]

Sure, I think my concerns about the harshness of that rules clarification has to do with implementing it without the player's prior knowledge. I think any player who knows that is the ruling would reasonably choose a cantrip over "wasting" a spell slot.

I think the players should already expect that's the way it works. Spell slots already get expended when the spell gets used against an invalid target, like when a caster uses charm person on a "monster" or that time I cast stone shape on an impenetrable wall of thorns (I was hoping it was just an incredibly lifelike sculpture)

 

[Oofta]

Low level force damage spells are a bit weird in what they can target, but I think it's pretty easy to justify. You can apply quite a bit of electricity to a piece of metal without harming it, more than enough to kill a person or at least cause significant burns. Enough energy though and that metal will melt.

Same with fire spells, unless the target is extremely flammable low level fire spells are just a quick blast. May leave a scorch mark but that's it. It's the difference between passing your finger through the flame of a candle and the flame of a cutting torch. The former doesn't hurt, I wouldn't try the latter unless you want a trip to the doctor.

As far as the OP, I'd probably have the spell go off but then indicate that they splash off the statue harmlessly. It is interesting that they changed their mind about spells with invalid targets costing a spell slot in Xanathar's, there was a podcast at one time that said that the intent was that they would not.

Also, I let players call for intitiative any time they want. In this case they were attacking the gazebo, I wouldn't want to disillusion them.

 

[Morrus]

Yeah. I would still allow PCs to attempt to attack an invalid target it just wouldn’t have any effect.

 

[iserith]

I think the players should already expect that's the way it works. Spell slots already get expended when the spell gets used against an invalid target, like when a caster uses charm person on a "monster" or that time I cast stone shape on an impenetrable wall of thorns (I was hoping it was just an incredibly lifelike sculpture)

I fully expect someone to call "reversies." Or worse, "backsies." Then we'd have to review the record to see if someone had previously touched blue to make it true. And gods forbid someone double-stamped it. It's just a mess.

 

[UngeheuerLich]

Low level force damage spells are a bit weird in what they can target, but I think it's pretty easy to justify. You can apply quite a bit of electricity to a piece of metal without harming it, more than enough to kill a person or at least cause significant burns. Enough energy though and that metal will melt.

Same with fire spells, unless the target is extremely flammable low level fire spells are just a quick blast. May leave a scorch mark but that's it. It's the difference between passing your finger through the flame of a candle and the flame of a cutting torch. The former doesn't hurt, I wouldn't try the latter unless you want a trip to the doctor.

As far as the OP, I'd probably have the spell go off but then indicate that they splash off the statue harmlessly. It is interesting that they changed their mind about spells with invalid targets costing a spell slot in Xanathar's, there was a podcast at one time that said that the intent was that they would not.

Also, I let players call for intitiative any time they want. In this case they were attacking the gazebo, I wouldn't want to disillusion them.

Or a phaser on stun. I would not want players to systematically target and identify without resource cost.

I'd also not allow casting of cantrip without pause. I think it is as streneous as using a tool.
And it is not without precedent.
During a combat you might use dash every round. When combat is over and you start a chase, suddenlx you might get exhaustion.
I think cantrip rules are written for combats which are not taking longer than a minute or so. So even if they are at will, you can't keep it up without pause.

 

[Azzy]

I don't see the problem with this as it's not really something that will come up often or be abusive unless the DM is spamming gargoyles, mimics, or whatnot.