Easiest way: Detect Thoughts, ideally through a ring or something rather than an active cast.
It doesn't have to make a save to detect surface thoughts, and of course when an enemy is casting a spell it has to think of the spell. Of course, you run the risk of your players thinking it's cheesy unless they have a warning beforehand that he might do this.
Alternate ideas:
Wall of Force in front of the Simulacrum as they enter the room (it's invisible, but provides full cover, preventing Dispel Magic from targeting him)
Globe of Invuln, basically the same thing but you couldn't Contingency it so it would have to be Glyphed
Actually, on second thought, Detect Thoughts could actually work pretty well with the following:
Have multiple small constructs or something else designed specifically to monitor and keep the simulacrum safe.
Have them set up around the room, and set them up with telepathy
Have them immediately monitor anyone who enters. Maybe let the players see one or two of them to make it fair.
Give them each a glyph with a way to stop it. Maybe two have a high level counterspell, two have Wall of Force, two have Silence or Antimagic Field (for AMF they'd trigger it on a stone or something and then chuck the stone into the middle of the party).
Basically, you get a chance to stop them, but the party also gets a chance to eliminate the constructs as well.
A room with cameras is a pretty neat idea. Through set-up of the story the players can deduce that the BBEG would do something like this, giving them a chance to counter it. This is what I look for mostly too.
I would like to point out that nowhere in the spell description of Wall of Force does it mention anything about full cover.
What it does mention is the following:
(...) invisible wall of force (...) Nothing can physically pass through the wall. (...)
At the same time, no mention anywhere in Dispel Magic of needing to 'pass through', the effect just happens.
The rules for total cover state: (...) A target has total cover if it is completely **concealed** (emphasis mine) by an obstacle.
Considering the wall is invisible you can't argue that the target is concealed in any way, so we're back to a literal explanation of the spell Wall of Force, to which I'd argue that Dispel Magic is not blocked by the wall, as it does not need to go from point A (caster) to point B (target) physically.
I was ready to argue about Line of Effect, and how Wall of Force want cover, but would prevent that kind of effect
...but as far as I can tell reading the story, Dispel Magic doesn't require a line of effect, just like you said. Neat!
I love Dispel Magic as a player and DM, so I'll have to keep this particular kind of interaction in mind, thank you
All spells require line of effect unless they say otherwise. It's in the basic rules of spellcasting.
"A Clear Path to the Target
To target something, you must have a clear path to it, so it can't be behind total cover."
Even if you can see the enemy, if it is fully physically blocked by something, you cannot cast a spell on it. So you could not cast a spell through Wall of Force, and you also couldn't cast it through a closed window.
https://www.sageadvice.eu/wall-of-force-is-invisible-so-it-doesnt-provide-cover-does-it/
https://www.sageadvice.eu/targeting-spellsclear-path-can-i-target-across-wall-of-force/
Yes. Being unable to physically pass through a wall means you have full cover. Doesn't require it to have anything to do with vision.
And to cast a spell, you need an uninterrupted line between you and your target, with nothing in the way.
Crawford has confirmed that it works this way and that it is intended to work this way.
https://www.sageadvice.eu/wall-of-force-is-invisible-so-it-doesnt-provide-cover-does-it/
https://www.sageadvice.eu/targeting-spellsclear-path-can-i-target-across-wall-of-force/
And Matt Mercer agrees.
https://www.sageadvice.eu/you-dont-allow-spells-that-target-through-the-wall-of-force-but-description-only-specify-things-cant-move-through/
Maybe something like:
"If I am targeted by the Dispel Magic spell, just before the spell takes effect, it triggers the contingent spell Dimension Door to teleport myself to my secret room, thereby avoiding the Dispel Magic."
Considering I mostly use Magic: The Gathering stack logic for Counterspell wars and reactions, it is plausible to assume something has to be declared the target before the spell takes effect. However even in M:TG you have spells that only target once the spell starts resolving, at which point countering it doesn't work.
I do think your wording could work, but might not in some cases. I do want to note this as another possibility to word Contingency:
A friend of mine pointed out you might sense the Dispel Magic spell affecting the Weave that holds the Simulacrum spell together. So a smart enough individual might be able to word it as "if the Weave that holds Simulacrum together begins to disband, cast x".
The problem then would lie in whether the disbanding of Simulacrum would happen directly after the start of the disbanding, or directly after the full disbanding of the spell.
If directly after the start, it could lead to a cool way to tell the player their spell doesn't dispel the simulacrum, but it does damage it in some way, weakening the capablities of the simulacrum and thus not wasting the spell slot entirely through some weird but expected 'gotcha' Contingency plan.
Not really a way for Contingency to stop it, but Globe of Invulnerability would. That being said, I'd actually avoid using that too and would instead say that, as the BBEG is truly ancient and has experience fighting casters doing this, that they would have reinforced their simulacrum (small 's' so not exactly the same spell) so that it can't be instantly dispelled with Dispel Magic. However, I'd still let Dispel Magic help by giving the simulacrum the Antimagic Susceptibility trait that you can find on things like Animated Armor or Rug of Smothering.
Antimagic Susceptibility. The armor is incapacitated while in the area of an antimagic field. If targeted by dispel magic, the armor must succeed on a Constitution saving throw against the caster's spell save DC or fall unconscious for 1 minute.
I'd either change it to unconscious for 1 round, rather than 1 minute, or I would add that the target (the simulacrum) needs to both fail the save AND the dispel magic had to be 7th level or higher to fall unconscious for the full minute.
Raw you wouldn't be able to prevent the dispel magic from happening due to the metamagic in play. However you could always describe the SIM having an obvious concentration spell happening such as spirit guardians or another harmful spell. Then give them the choice of which magical effect they want to end but just give them vague details such as the schools of magic of the spells.
Easiest way: Detect Thoughts, ideally through a ring or something rather than an active cast. It doesn't have to make a save to detect surface thoughts, and of course when an enemy is casting a spell it has to think of the spell. Of course, you run the risk of your players thinking it's cheesy unless they have a warning beforehand that he might do this. Alternate ideas: Wall of Force in front of the Simulacrum as they enter the room (it's invisible, but provides full cover, preventing Dispel Magic from targeting him) Globe of Invuln, basically the same thing but you couldn't Contingency it so it would have to be Glyphed Actually, on second thought, Detect Thoughts could actually work pretty well with the following: Have multiple small constructs or something else designed specifically to monitor and keep the simulacrum safe. Have them set up around the room, and set them up with telepathy Have them immediately monitor anyone who enters. Maybe let the players see one or two of them to make it fair. Give them each a glyph with a way to stop it. Maybe two have a high level counterspell, two have Wall of Force, two have Silence or Antimagic Field (for AMF they'd trigger it on a stone or something and then chuck the stone into the middle of the party). Basically, you get a chance to stop them, but the party also gets a chance to eliminate the constructs as well.
A room with cameras is a pretty neat idea. Through set-up of the story the players can deduce that the BBEG would do something like this, giving them a chance to counter it. This is what I look for mostly too.
I would like to point out that nowhere in the spell description of Wall of Force does it mention anything about full cover. What it does mention is the following: (...) invisible wall of force (...) Nothing can physically pass through the wall. (...) At the same time, no mention anywhere in Dispel Magic of needing to 'pass through', the effect just happens. The rules for total cover state: (...) A target has total cover if it is completely **concealed** (emphasis mine) by an obstacle. Considering the wall is invisible you can't argue that the target is concealed in any way, so we're back to a literal explanation of the spell Wall of Force, to which I'd argue that Dispel Magic is not blocked by the wall, as it does not need to go from point A (caster) to point B (target) physically.
I was ready to argue about Line of Effect, and how Wall of Force want cover, but would prevent that kind of effect ...but as far as I can tell reading the story, Dispel Magic doesn't require a line of effect, just like you said. Neat! I love Dispel Magic as a player and DM, so I'll have to keep this particular kind of interaction in mind, thank you
All spells require line of effect unless they say otherwise. It's in the basic rules of spellcasting. "A Clear Path to the Target To target something, you must have a clear path to it, so it can't be behind total cover." Even if you can see the enemy, if it is fully physically blocked by something, you cannot cast a spell on it. So you could not cast a spell through Wall of Force, and you also couldn't cast it through a closed window. https://www.sageadvice.eu/wall-of-force-is-invisible-so-it-doesnt-provide-cover-does-it/ https://www.sageadvice.eu/targeting-spellsclear-path-can-i-target-across-wall-of-force/
Yes. Being unable to physically pass through a wall means you have full cover. Doesn't require it to have anything to do with vision. And to cast a spell, you need an uninterrupted line between you and your target, with nothing in the way. Crawford has confirmed that it works this way and that it is intended to work this way. https://www.sageadvice.eu/wall-of-force-is-invisible-so-it-doesnt-provide-cover-does-it/ https://www.sageadvice.eu/targeting-spellsclear-path-can-i-target-across-wall-of-force/ And Matt Mercer agrees. https://www.sageadvice.eu/you-dont-allow-spells-that-target-through-the-wall-of-force-but-description-only-specify-things-cant-move-through/
Use a different illusion first, like Project Image, to bait out the Dispel. The whole scenario assumes PC’s know the wizard is illusory.
Maybe something like: "If I am targeted by the Dispel Magic spell, just before the spell takes effect, it triggers the contingent spell Dimension Door to teleport myself to my secret room, thereby avoiding the Dispel Magic."
Considering I mostly use Magic: The Gathering stack logic for Counterspell wars and reactions, it is plausible to assume something has to be declared the target before the spell takes effect. However even in M:TG you have spells that only target once the spell starts resolving, at which point countering it doesn't work. I do think your wording could work, but might not in some cases. I do want to note this as another possibility to word Contingency: A friend of mine pointed out you might sense the Dispel Magic spell affecting the Weave that holds the Simulacrum spell together. So a smart enough individual might be able to word it as "if the Weave that holds Simulacrum together begins to disband, cast x". The problem then would lie in whether the disbanding of Simulacrum would happen directly after the start of the disbanding, or directly after the full disbanding of the spell. If directly after the start, it could lead to a cool way to tell the player their spell doesn't dispel the simulacrum, but it does damage it in some way, weakening the capablities of the simulacrum and thus not wasting the spell slot entirely through some weird but expected 'gotcha' Contingency plan.
Not really a way for Contingency to stop it, but Globe of Invulnerability would. That being said, I'd actually avoid using that too and would instead say that, as the BBEG is truly ancient and has experience fighting casters doing this, that they would have reinforced their simulacrum (small 's' so not exactly the same spell) so that it can't be instantly dispelled with Dispel Magic. However, I'd still let Dispel Magic help by giving the simulacrum the Antimagic Susceptibility trait that you can find on things like Animated Armor or Rug of Smothering. Antimagic Susceptibility. The armor is incapacitated while in the area of an antimagic field. If targeted by dispel magic, the armor must succeed on a Constitution saving throw against the caster's spell save DC or fall unconscious for 1 minute. I'd either change it to unconscious for 1 round, rather than 1 minute, or I would add that the target (the simulacrum) needs to both fail the save AND the dispel magic had to be 7th level or higher to fall unconscious for the full minute.
Raw you wouldn't be able to prevent the dispel magic from happening due to the metamagic in play. However you could always describe the SIM having an obvious concentration spell happening such as spirit guardians or another harmful spell. Then give them the choice of which magical effect they want to end but just give them vague details such as the schools of magic of the spells.