Return to Answer

Maybe you are giving too much information to your players about spells effects.

No.1 : They have no way to tell if the target was affected or not by the spell unless the result of the spell has noticeable/perceivable effects. The Eldritch blast example you are providing is a good one. Nothing says the Eldritch blasts 'fizzles' if the target is invalid. The blast goes and hits the target... there is not a 'HP bar' on top of the target's head and if someone wants to know if there was any adverse effect on the target, a Medecine check is required (which also takes time, at least 1 min each)... They will likely find that after spending 6 hours in the first room that this tactics is really, really inneficient, they will lack food, water, attract dozens of wandering monsters and miss most of their deadlines....

Ref: PHB P205

Unless a spell has a perceptible effect, a creature might not know it was targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

No.2: There is no way for caster to tell the difference between an invalid target and a valid target that made its saving throw. The resulting perceivable effect is often the same.

ref : XGE P85

If the spell normally has no effect on a target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn't attempt one (giving no hint that the creature is in fact an invalid target). Otherwise, you perceive that the spell did nothing to the target.

Lets take a look at 2 scenarios.

A) Eldritch blast cast at an object: The spells goes off normally, PC makes an attack roll, hits the object. Then needs to go inspect said object for any effect as it will not perceivable enough without perception or medecine check DC15. doing these checks will require at least 2 mins. 1 min for perception, 1 min for medecine. Reveal info based on check results

B) Eldritch blast cast at a Mimic The spells goes off normally, PC makes an attack roll, hits the mimic you apply damage without telling anything. If the mimic decides to stay hidden, they will need to approach and touch the creature to perform the Medecine and Perception check DC15 to determine if there is any damage. Mimic attacks then. Game over....

Conclusion: I suggest you review maybe the amount of information you give to your players when their characters cast spells, this issue will then resolve by itself.

Maybe you are giving too much information to your players about spells effects.

No.1 : They have no way to tell if the target was affected or not by the spell unless the result of the spell has noticeable/perceivable effects. The Eldritch blast example you are providing is a good one. Nothing says the Eldritch blasts 'fizzles' if the target is invalid. The blast goes and hits the target... there is not a 'HP bar' on top of the target's head and if someone wants to know if there was any adverse effect on the target, a Medecine check is required (which also takes time, at least 1 min each)... They will likely find that after spending 6 hours in the first room that this tactics is really, really inneficient, they will lack food, water, attract dozens of wandering monsters and miss most of their deadlines....

Ref: PHB P205

Unless a spell has a perceptible effect, a creature might not know it was targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

No.2: There is no way for caster to tell the difference between an invalid target and a valid target that made its saving throw. The resulting perceivable effect is often the same.

ref : XGE P85

If the spell normally has no effect on a target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn't attempt one (giving no hint that the creature is in fact an invalid target). Otherwise, you perceive that the spell did nothing to the target.

Lets take a look at 2 scenarios.

A) Eldritch blast cast at an object: The spells goes off normally, PC makes an attack roll, hits the object. Then needs to go inspect said object for any effect as it will not be perceivable enough without perception or medecine check DC15. Doing these checks will require at least 2 mins. 1 min for perception, 1 min for medecine. Reveal info based on check results

B) Eldritch blast cast at a Mimic: The spells goes off normally, PC makes an attack roll, hits the mimic you apply damage without telling anything. If the mimic decides to stay hidden, PC will need to approach and touch the creature to perform the Medecine and Perception check DC15 to determine if there is any effect. Mimic attacks then. Game over....

Conclusion: I suggest you review maybe the amount of information you give to your players when their characters cast spells, this issue will then resolve by itself.

Maybe you are giving too much information to your players about spells effects.

No.1 : They have no way to tell if the target was affected or not by the spell unless the result of the spell has noticeable/perceivable effects. The Eldritch blast example you are providing is a good one. Nothing says the Eldritch blasts 'fizzles' if the target is invalid. The blast goes and hits the target... there is not a 'HP bar' on top of the target's head and if someone wants to know if there was any adverse effect on the target, a Medecine check is required (which also takes time, at least 1 min each)... They will likely find that after spending 6 hours in the first room that this tactics is really, really inneficient, they will lack food, water, attract dozens of wandering monsters and miss most of their deadlines....

Ref: PHB P205

Unless a spell has a perceptible effect, a creature might not know it was targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

No.2: There is no way for caster to tell the difference between an invalid target and a valid target that made its saving throw. The resulting perceivable effect is often the same.

ref : XGE P85

If the spell normally has no effect on a target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn't attempt one (giving no hint that the creature is in fact an invalid target). Otherwise, you perceive that the spell did nothing to the target.

Conclusion: I suggest you review maybe the amount of information you give to your players when their characters cast spells, this issue will then resolve by itself.

Maybe you are giving too much information to your players about spells effects.

No.1 : They have no way to tell if the target was affected or not by the spell unless the result of the spell has noticeable/perceivable effects. The Eldritch blast example you are providing is a good one. Nothing says the Eldritch blasts 'fizzles' if the target is invalid. The blast goes and hits the target... there is not a 'HP bar' on top of the target's head and if someone wants to know if there was any adverse effect on the target, a Medecine check is required (which also takes time, at least 1 min each)... They will likely find that after spending 6 hours in the first room that this tactics is really, really inneficient, they will lack food, water, attract dozens of wandering monsters and miss most of their deadlines....

Ref: PHB P205

Unless a spell has a perceptible effect, a creature might not know it was targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

No.2: There is no way for caster to tell the difference between an invalid target and a valid target that made its saving throw. The resulting perceivable effect is often the same.

ref : XGE P85

If the spell normally has no effect on a target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn't attempt one (giving no hint that the creature is in fact an invalid target). Otherwise, you perceive that the spell did nothing to the target.

Lets take a look at 2 scenarios.

A) Eldritch blast cast at an object: The spells goes off normally, PC makes an attack roll, hits the object. Then needs to go inspect said object for any effect as it will not perceivable enough without perception or medecine check DC15. doing these checks will require at least 2 mins. 1 min for perception, 1 min for medecine. Reveal info based on check results

B) Eldritch blast cast at a Mimic The spells goes off normally, PC makes an attack roll, hits the mimic you apply damage without telling anything. If the mimic decides to stay hidden, they will need to approach and touch the creature to perform the Medecine and Perception check DC15 to determine if there is any damage. Mimic attacks then. Game over....

Conclusion: I suggest you review maybe the amount of information you give to your players when their characters cast spells, this issue will then resolve by itself.

Maybe you are giving too much information to your players about spells effects.

No.1 : They have no way to tell if the target was affected or not by the spell unless the result of the spell has noticeable/perceivable effects

Ref: PHB P205

Unless a spell has a perceptible effect, a creature might not know it was targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

No.2: There is no way for caster to tell the difference between an invalid target and a valid target that made its saving throw. The resulting perceivable effect is often the same.

ref : XGE P85

If the spell normally has no effect on a target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn't attempt one (giving no hint that the creature is in fact an invalid target). Otherwise, you perceive that the spell did nothing to the target.

Conclusion: I suggest you review maybe the amount of information you give to your players when their characters cast spells, this issue will then resolve by itself.

Maybe you are giving too much information to your players about spells effects.

No.1 : They have no way to tell if the target was affected or not by the spell unless the result of the spell has noticeable/perceivable effects. The Eldritch blast example you are providing is a good one. Nothing says the Eldritch blasts 'fizzles' if the target is invalid. The blast goes and hits the target... there is not a 'HP bar' on top of the target's head and if someone wants to know if there was any adverse effect on the target, a Medecine check is required (which also takes time, at least 1 min each)... They will likely find that after spending 6 hours in the first room that this tactics is really, really inneficient, they will lack food, water, attract dozens of wandering monsters and miss most of their deadlines....

Ref: PHB P205

Unless a spell has a perceptible effect, a creature might not know it was targeted by a spell at all. An effect like crackling lightning is obvious, but a more subtle effect, such as an attempt to read a creature’s thoughts, typically goes unnoticed, unless a spell says otherwise.

No.2: There is no way for caster to tell the difference between an invalid target and a valid target that made its saving throw. The resulting perceivable effect is often the same.

ref : XGE P85

If the spell normally has no effect on a target that succeeds on a saving throw, the invalid target appears to have succeeded on its saving throw, even though it didn't attempt one (giving no hint that the creature is in fact an invalid target). Otherwise, you perceive that the spell did nothing to the target.

Conclusion: I suggest you review maybe the amount of information you give to your players when their characters cast spells, this issue will then resolve by itself.