I just realized that in high level adventures (like 10th level or above), both the enchanter and illusionist subclasses are at a disadvantage because a lot of the creatures the party faces will be immune to illusion and enchantment/charm spells. Does anyone know how to resolve this? Or is this really not a problem at all?

I don't high level characters systematically encounter creatures immune to illusions and enchantment. I mean some may be, but many monsters and NPCs do not. 

Characters may have features that vary in usefulness over time that's life.

Regarding Charm, the reason so many high level monsters are immune to Charm is to prevent them from being taken over by Dominate effects - spells like Dominate Monster, which allow you to take control of a monster.  Dominate effects can, in a single turn, make a hard fight far more trivial—best case (for the monsters) the big guy wastes a turn, worst case, the big guy, with the power level of a high level monster, smacks around one of its allies, dealing a big chunk of damage while also wasting a turn.

One easy solution is to read “Immune to Charm” on high level monsters as “Immune to Dominate” and allow other effects that Charm function as normal.  That allows the player to enjoy the class they have chosen, while preserving the underlying reason the monster had the charm immunity in the first place.

For Illusion spells, your big issues are going to be Blindsight, Tremorsense, and Truesight, since those are the main ways high level monsters can see past illusions.  Blindsight can often be bypassed by using auditory illusions, tremorsense by using areal ones.  Truesight is the biggest problem - that might be one where you want to downgrade the monster to having Darkvision or such, to ensure your player can still use their class.

Another option would be to give the player a legendary magic item allowing them to do illusions which work against these sights.  Rather than just automatically working, the item could say the creature with Truesight has to pass a save to see through the illusion, and can retry the save at the end of each of its turns.

Thank you. Really appreciate the advice.

Thats why wizards subclasses aren’t restricted in which spells they can take, and can cast spells from any school. Even an Illusionist or Enchanter can cast fireball. You gotta realize, not all subclasses, especially not all Wizard subclasses are designed for combat. Those subclasses have distinct advantages in social encounters over subclasses like Evoker or Necromancer.

Quote from IamSposta >>

Thats why wizards subclasses aren’t restricted in which spells they can take, and can cast spells from any school. Even an Illusionist or Enchanter can cast fireball. You gotta realize, not all subclasses, especially not all Wizard subclasses are designed for combat. Those subclasses have distinct advantages in social encounters over subclasses like Evoker or Necromancer.

 I realize that. It’s just that when my friend group runs a campaign, there’s usually at least some combat, and I’m worried my enchanter or my illusionist will be at a disadvantage in high level fights.

Almost every campaign has at least some combat, that’s really what D&D is designed for. Don’t think of it as the Enchanter or Illusionist have any disadvantages in combat because they don’t. It’s just that they don’t have any special advantages in combat either. Their special advantages are better suited to other situations is all. It’s not like an Abjurer or Evoker has any disadvantages in social encounters, they just don’t get any special advantages in those situations either. Right? They can still cast charm person or major image if they want to, they just don’t get any extra stuff when doing so. Same thing with Enchanters and Illusionists in combat. They can still cast shield or disintegrate, same as any wizard. That’s why it’s important to have a diversified spell list.

The problem goes beyond combat.  Part of the appeal of playing Illusionist or Enchanting Wizards is figuring out how to avoid combat in the first place by using the spells you specialised in.  It also is in the ability to end combat by manipulating events.  At high levels, however, things like charm immunity are so absurdly common that your efficacy at even the non-combat aspects of your subclass starts to suffer, even outside of combat.

This is fundamentally different than something like an Evocation Wizard.  Evoker Wizards always have the option of playing their subclass to its full extent.  Sure, they might not have any specific subclass tools for out-of-combat shenanigans… but they always can say “Hey,, I’m an Evocation Wizard, and I don’t want to talk to you, sooooo Fireball.”  That might cause lots of problems, and there might be social compact reasons not to do that, but roleplaying is the impediment there, not the rules.

For Illusion and Enchantment Wizards, the rules are the problem.  “Sorry, but this is the tenth creature  in a row you’ve run into in a row with charm immunity, because I am playing a premade adventure and WotC overly relies upon Charm immunity at high levels” feels pretty darn awful.  That’s the game telling you over and over and over again “sorry bud, you picked the wrong subclass, either use spells you didn’t design your character around, or twiddle your thumbs, cause your enchantment magic isn’t welcome at this tier of play.”

(Sidebar: forgot to add this advice to my first post since it was so obvious I did not even cross my mind—you can always just use different monsters.  Most high level monsters have Charm immunity or something else that interferes with these subclasses, but there are many that do not. You can always use those instead.)

Quote from Caerwyn_Glyndwr >>

This is fundamentally different than something like an Evocation Wizard.  Evoker Wizards always have the option of playing their subclass to its full extent.  Sure, they might not have any specific subclass tools for out-of-combat shenanigans… but they always can say “Hey,, I’m an Evocation Wizard, and I don’t want to talk to you, sooooo Fireball.”  That might cause lots of problems, and there might be social compact reasons not to do that, but roleplaying is the impediment there, not the rules.

 

There are just as many monsters that have resistance or immunity to fire, cold, lightning...which also stresses that you should have a diverse spell list.

Quote from Wysperra >>

Quote from Caerwyn_Glyndwr >>

This is fundamentally different than something like an Evocation Wizard.  Evoker Wizards always have the option of playing their subclass to its full extent.  Sure, they might not have any specific subclass tools for out-of-combat shenanigans… but they always can say “Hey,, I’m an Evocation Wizard, and I don’t want to talk to you, sooooo Fireball.”  That might cause lots of problems, and there might be social compact reasons not to do that, but roleplaying is the impediment there, not the rules.

 

 

There are just as many monsters that have resistance or immunity to fire, cold, lightning...which also stresses that you should have a diverse spell list.

 
“You have to use use chained lightning instead of fireball” is a clearly different circumstance than “Hey, basically every spell you might use that targets the enemy is useless because they have a single blanket immunity to Charmed.”

Quote from Caerwyn_Glyndwr >>

Quote from Wysperra >>

Quote from Caerwyn_Glyndwr >>

This is fundamentally different than something like an Evocation Wizard.  Evoker Wizards always have the option of playing their subclass to its full extent.  Sure, they might not have any specific subclass tools for out-of-combat shenanigans… but they always can say “Hey,, I’m an Evocation Wizard, and I don’t want to talk to you, sooooo Fireball.”  That might cause lots of problems, and there might be social compact reasons not to do that, but roleplaying is the impediment there, not the rules.

 

 

There are just as many monsters that have resistance or immunity to fire, cold, lightning...which also stresses that you should have a diverse spell list.

 
“You have to use use chained lightning instead of fireball” is a clearly different circumstance than “Hey, basically every spell you might use that targets the enemy is useless because they have a single blanket immunity to Charmed.”

 
Why would you not have spells that do things besides charming creatures? Just because you’re an Enchanter, you should still have some combat capabilities that don’t rely solely upon 1 condition. It isn’t good for anyone to be a 1-trick pony unless that trick is straight smashing things, and even then it’s handy to be able to do other stuff too.

Quote from Caerwyn_Glyndwr >>

Quote from Wysperra >>

Quote from Caerwyn_Glyndwr >>

This is fundamentally different than something like an Evocation Wizard.  Evoker Wizards always have the option of playing their subclass to its full extent.  Sure, they might not have any specific subclass tools for out-of-combat shenanigans… but they always can say “Hey,, I’m an Evocation Wizard, and I don’t want to talk to you, sooooo Fireball.”  That might cause lots of problems, and there might be social compact reasons not to do that, but roleplaying is the impediment there, not the rules.

 

 

There are just as many monsters that have resistance or immunity to fire, cold, lightning...which also stresses that you should have a diverse spell list.

 
“You have to use use chained lightning instead of fireball” is a clearly different circumstance than “Hey, basically every spell you might use that targets the enemy is useless because they have a single blanket immunity to Charmed.”

Enchantment spells that are not affected by Charmed immunity:

Friends
Mind Sliver
Hideous Laughter
Silvery Barbs
Gift of Gab
Hold Person
Jim’s Glowing Coin
Tasha's Mind Whip
Antagonize
Catnap
Enemies Abound
Confusion
Raulothim's Psychic Lance
Hold Monster
Synaptic Static
Antipathy/Sympathy
Feeblemind
Power Word Stun
Power Word Kill
Psychic Scream

Thanks guys. This is really helpful. My enchanter has a diversified spell list, it’s just I get frustrated when she can’t use the enchantment/charm spells she specializes in because all the monsters have immunity to it.

217 monster statblocks with True Sight. This includes dupes from Legacy and Variants, because no way I'm going through monsters one by one.

There are 2,757 monster statblocks total.

Statistically speaking the chances of cross monsters immune to illusions is very low. 

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So you shouldn't be having much of an issue unless your DM is deliberately trying to counter you specifically - in which case, nothing you do matters and your choices are irrelevant and you're in "talk to DM or leave" territory.

I guess I just feel like we’ve been running into a lot of creatures who are immune to mind-affecting spells, which includes a lot of enchantment and illusion spells.

DMs who struggle to provide long-running games without relying on combat will struggle with Illusion and some Enchantment spells. Many DMs are in the "combat must challenge players" mindset, which isn't wrong necessarily but sometimes combat should be what is for story reasons - if the players have a resource to trivialise it, so be it. It's hard for some DMs to just let it go. DMs do have multiple options for combat against enchanters and illusions that don't rely on charm immunity and truesight, such as multiple mobs - the number your illusions/charms can affect is limited, there's dispel magic, antimagic, traps, hazards, and more. It's not an easy thing, sure enough, but there are plenty of options. 

If you're encountering this enough to spoil your fun, where it is making you feel like you're never using the features you invested your character into, then your best option is talk to the DM. They might not realise what other options they have or may be relying too much on combat. Open discussion with them is the only way, really. 

While I agree with everyone saying you should have lots of different kinds of spells ready, the issue to my mind would be more the subclass abilities. Not so much for illusion, but enchantment’s subclass stuff doesn’t work against creatures with charm immunity, so at that point, you really don’t have a subclass. Any wizard should still have lots of tools in the toolbox when it comes to spells, and have lots of other options, but it does suck to just negate the subclass powers. 

Quote from Cyb3rM1nd >>

DMs who struggle to provide long-running games without relying on combat will struggle with Illusion and some Enchantment spells. Many DMs are in the "combat must challenge players" mindset, which isn't wrong necessarily but sometimes combat should be what is for story reasons - if the players have a resource to trivialise it, so be it. It's hard for some DMs to just let it go. DMs do have multiple options for combat against enchanters and illusions that don't rely on charm immunity and truesight, such as multiple mobs - the number your illusions/charms can affect is limited, there's dispel magic, antimagic, traps, hazards, and more. It's not an easy thing, sure enough, but there are plenty of options. 

If you're encountering this enough to spoil your fun, where it is making you feel like you're never using the features you invested your character into, then your best option is talk to the DM. They might not realise what other options they have or may be relying too much on combat. Open discussion with them is the only way, really. 

 Thank you

Quote from IamSposta >>

Thats why wizards subclasses aren’t restricted in which spells they can take, and can cast spells from any school. Even an Illusionist or Enchanter can cast fireball. You gotta realize, not all subclasses, especially not all Wizard subclasses are designed for combat. Those subclasses have distinct advantages in social encounters over subclasses like Evoker or Necromancer.

 I have a question, how do you link a spell like that? It would be very handy if I knew how.

Quote from WoodsGirl0402 >>

I guess I just feel like we’ve been running into a lot of creatures who are immune to mind-affecting spells, which includes a lot of enchantment and illusion spells.

 Your DM might be making some assumptions based on what monsters were immune to in older editions. I say this because "mind-affecting" was a descriptor for spells and abilities in 3.5e specifically, and crucially, it isn't in 5e.

Edit: As an illustration, the Giant Centipede monster in 3.5e had "Vermin Traits," which meant (among other things) that it was categorically immune to mind-affecting spells on account of its tiny bug brain. In 5e, the Giant Centipede isn't immune to anything.