How to deal with high AC PC's?

[braveheart]

In my campaign I've noticed that some of the PC's have gotten their AC's incredibly high. Specifically the fighter and paladin. The easy fix is to give everything a higher to hit bonus, but to make something have a 40% chance of hitting the tin cans, it will have a 100% chance to hit the wizard. The players have communicated a desire to use their high AC to protect the squishy casters, but often fail to establish a tactical position that would allow them to actually defend the back line, and there is no reason for a creature to attack something it can't hit when it can reach targets who make easier prey/victims. I guess I'd just like to hear how other DM's deal with large AC disparities. Because I've noticed frustration when my players are unable to defend the easier targets.

TL DR how do you deal with one character getting 22 AC and another having 13?

[Bobthewizard]

I don't really worry about adjusting to hit bonuses to adjust to the party.

I have dumb monsters attack the high AC PCs, which makes them feel good about their choice, but smart monsters try to move around them to attack the wizard if they can, then I let the party try to adjust their tactics.

I don't hide this from my players either. I tell them ahead of time that just like they try to do, tactically proficient monsters will try to take out spell casters first. The wizard should be afraid of combat. They should be hiding and dodging as much as possible.

[nickl_2000]

You put in some casters that force them to make saves instead of targetting their AC. However, not all monsters should have this, the PCs expended resources to get a good AC let them enjoy it.

[Kireban]

Nothing to do except using monsters that target saves or using spells/damage that cannot be avoided.
The only way for them to "protect" squishy pcs is by blocking the way to them/ taking the fight far enough/ getting close to ranged units so that attacks against the squishy will get disadvantage. If they dont do that then there is nothing you can do.
If their ac is too much for you, you can always just attack them with tons of Zorbos wearing little iron shoes.

[J-H]

Yep, this is normal.
Also a higher volume of attacks, so that something gets through. Scorching Ray, lots of archery, etc.

Breath weapons and anything else targeting saves bypasses AC.

[lall]

Grapple them and find the nearest cliff or other hazard.

[Mikal]

If your players feel frustration at not protecting their teammates then they need to spend resources that force the enemy to not go after the easier targets.

As you said they don’t go into tactical places that can protect the others. I’m also guessing they aren’t taking advantage of feats, fighting styles, and class features which enhance the protection ability, just assuming a high AC means they’ll automatically protect others.

It doesn’t. It only protect themselves. Some enemies may be dumb and attack the obvious then can, many won’t when easier prey is in reach.

Tl;dr your players need to get good at protecting if they want to actually protect

[SirGraystone]

Frustration in players is never good.

I have an high AC player in my campaign, most of the time I let him get the attacks from most of the monsters, that make him happy to player is "role" as a tank. But at time he's been taken out of fight by magic, either by charm forcing him to attack his teamate or by banishment, but that's not something to be done too often as its no fun to sit out of fight with nothing to do. Or I just throws more monsters then he can tank at the same time and let the extra attacks the rest of the group.

[Eldariel]

First of all, it depends on the monster. Now, some monsters have high attack bonus, others have save-targeting effects, others have autohit effects, etc. General ways for different encounters to go:
1) Zombies, Skeletons, many beasts/monstrocities, etc. will hit the first guy. These are instinctual or programmed creatures with little in terms of variety in their combat style. They'll always use their default strategy (attack, grapple, trip, whatever it may be) and it may or may not work. Against these guys, high AC is great.

2) Aberrations, outsiders, some monstrocities, etc. These guys often have abilities. They are also pretty able to adapt on the fly. They don't think like humanoids but they do often have tactical acumen; they'll pick their targets, they'll wait for the right moment to attack, they try to avoid the obvious steel wall in favour of the squishy in the back, etc. This is circumstantial and obviously depends on the individual creature but as a rule they'll use abilities against those they believe it might work (guy clad in steel is generally weaker of will/not that mobile and thus save-or-X effects should be thrown at them, while biting a steel wall is pretty futile unless it's a big thing that can bite/hit through it like many giants or bigger monstrocities, which don't mind attacking a steel wall).

3) Humanoids, giants, etc. These guys often have organisations. That is to say, it's not just a set of one type of creature but a combination of spellcasters, archers, melees, etc. This opens up a lot of tactics: instead of just hitting the melee guys they can focus fire often on the ranged types while their melees keep the steel wall occupied (a reversal of roles), sneaks might position so that they have access to the backline, spellcasters can bring down the melee with save-or-X effects or isolate them with walls/Sleet Storms/etc. while the warriors focus on the party spellcasters, etc. Alternatively, the spellcasters can buff the warriors so they can punch through the steel walls.

For example, I started my LMoP party on level 3. To compensate, the Goblins had some Clerics. Bless made 'em able to hit the 20 AC Fighter and 22 AC Shielding Wizard occasionally, and Command enabled attacking at advantage or removing the frontline so they got access to the backline. Guiding Bolt was a really brutal but kinda all-or-nothing kind of attack (they did land one).

[Zuras]

It seems like your problem isn’t the high ACs, it’s that the PCs don’t have a way of effectively tanking to keep opponents off their back line once they realize the front line is too hard to hit. Controlling enemy movement without spells, feats or special subclass features is quite difficult in 5e.

Tactically, for greater odds of success against the front line ranks you can have opponents try to shove them prone for advantage, or make sure you use a mix of enemies that includes some with save based attacks. Don’t go overboard—there should be plenty of threats AC guards against, but 3 Wights and a Flameskull will go further than 5 Wights, for example.

[Specter]

You answered your own dilemma.


The players have communicated a desire to use their high AC to protect the squishy casters, but often fail to establish a tactical position that would allow them to actually defend the back line, and there is no reason for a creature to attack something it can't hit when it can reach targets who make easier prey/victims.

All intelligent enemies would much rather make their attacks hit, especially if it's against a feeble character, and especially it that character is a caster (everyone who has any battle knowledge knows that they can easily turn a fight upside down).

So you don't really have to 'manage' anything. A character invested in AC (at the expense of not wielding heavy weapons, for example), so let them enjoy it. Of course, that creates a problem for the squishies that they'll have to figure out, not you.

[Friv]

In my campaign I've noticed that some of the PC's have gotten their AC's incredibly high. Specifically the fighter and paladin. The easy fix is to give everything a higher to hit bonus, but to make something have a 40% chance of hitting the tin cans, it will have a 100% chance to hit the wizard. The players have communicated a desire to use their high AC to protect the squishy casters, but often fail to establish a tactical position that would allow them to actually defend the back line, and there is no reason for a creature to attack something it can't hit when it can reach targets who make easier prey/victims. I guess I'd just like to hear how other DM's deal with large AC disparities. Because I've noticed frustration when my players are unable to defend the easier targets.

TL DR how do you deal with one character getting 22 AC and another having 13?

Don't treat the battle like a game, treat it like a confusing melee with many NPCs having poor intel.

The reason that the monster keeps swinging at the fighter even though there's someone squishy in the back is because there is a big guy in its face with a freaking sword. Unless it is a tactical genius, it does not want that at its back! And it doesn't necessarily know the warrior's AC offhand. Even if the two lead fighters aren't establishing a tactical line that makes it impossible to get past them, as long as they aren't fighting either (a) massive groups that will swarm them and keep going or (b) highly mobile and intelligent tactical enemies, they're going to start by hitting the thing that is right there hitting back.

So let a lot of your monsters not run past the front line, because if they do they're going to be caught between the front line and the squishies. And then let those monsters have a low enough to-hit bonus that a lot of their attacks whiff. And then let the PCs feel good that attacks are whiffing instead of hitting the wizard. And then you have succeeded.

And as an aside: 22 AC is good, but it shouldn't be "monsters can't possibly hit" good. What level are you dealing with? Maybe you should use smaller groups of higher-CR enemies, so that it's easier for the frontline to engage them but also easier for them to do some damage?

*EDIT* Also, multi-attacks. A lot of enemies attack multiple times, which you can use to allow some attacks to whiff but others to hit. For example, a manticore is only CR 3. It can jump the toughest-looking enemy and attack three times; even if each attack only has a 1-in-5 chance of hitting, the chance of something hitting is better than 50/50. A Knight could engage the enemy paladin to cover his allies, while shouting encouragement at the people fighting the Fighter, and leaving a backrow person of his own to fire arrows at the wizard. And so on.

[Composer99]

In my campaign I've noticed that some of the PC's have gotten their AC's incredibly high. Specifically the fighter and paladin. The easy fix is to give everything a higher to hit bonus, but to make something have a 40% chance of hitting the tin cans, it will have a 100% chance to hit the wizard. The players have communicated a desire to use their high AC to protect the squishy casters, but often fail to establish a tactical position that would allow them to actually defend the back line, and there is no reason for a creature to attack something it can't hit when it can reach targets who make easier prey/victims. I guess I'd just like to hear how other DM's deal with large AC disparities. Because I've noticed frustration when my players are unable to defend the easier targets.

TL DR how do you deal with one character getting 22 AC and another having 13?

I don't see that you need to give monsters a higher to-hit bonus. If your tanky tanks made the effort to have such high ACs, let them be hard to hit with attacks that target AC.

However, their choices have consequences. If they bulked up on AC at the expense of options that let them control the movement of their enemies, such as the Sentinel feat, that was a choice they made to be less effective at protecting the squishies. Especially if they are exacerbating that choice by not positioning themselves satisfactorily, or if the squishies are exacerbating it by not making an effort to boost their own ACs, whether through items or spells.

That stated, it doesn't follow that you have to constantly rub those consequences in their faces. Others have already stated some reasons why monsters might not think to target the squishies, or might choose not to. Here's a different reason why even intelligent monsters might see fit to make at least some effort to fight the tanky tanks at the expense of going after squishies: Leaving that plate-wearing, greatsword wielding, divine-smiting or Action-Surging mo-fo alone to their own devices is bad. Maybe even really bad. It might feel good making the wizard fall down because you stuck them in the gut, but if you didn't do anything to stop the steel-plated juggernaut while you were at it you're probably still going to die horribly - you just die by getting your head caved in instead of by getting it 'asploded (https://youtu.be/R22zSrpeSA4?t=67) by a spell. And chances are that steel-plated juggernaut or one of their friends has a potion or spell that will get the wizard back up on their feet, so you might even die for nothing (at least from your perspective; the PCs might bemoan the resource expenditure).

Some monsters are better at dealing with this problem than others, especially at higher CRs. This is why your PCs need to be good at working together, to make sure no monster can ever feel safe leaving a steel-plated juggernaut alone. But to some extent that is on them to figure out.

[MaxWilson]

In my campaign I've noticed that some of the PC's have gotten their AC's incredibly high. Specifically the fighter and paladin. The easy fix is to give everything a higher to hit bonus, but to make something have a 40% chance of hitting the tin cans, it will have a 100% chance to hit the wizard. The players have communicated a desire to use their high AC to protect the squishy casters, but often fail to establish a tactical position that would allow them to actually defend the back line, and there is no reason for a creature to attack something it can't hit when it can reach targets who make easier prey/victims. I guess I'd just like to hear how other DM's deal with large AC disparities. Because I've noticed frustration when my players are unable to defend the easier targets.

TL DR how do you deal with one character getting 22 AC and another having 13?

Well, you could give some enemies a value system that makes them value 1-on-1 combat and be reluctant to steal someone else's kill. If someone is already fighting the AC 22 guy they can look elsewhere.

The players can retaliate in various ways, e.g. by having the fighter grapple the guy who's looking elsewhere for a fight, which might outrage and insult the guy who's already fighting him.

Illusions like Disguise Self/Seeming can also be a lot of fun against intelligent enemies. Make the beefy plate-armored guys look like frail unarmored scholars, make wizards look like The Mountain That Rides. (Can backfire.)

[MrStabby]

So I never have this problem, but I do run high magic worlds. In my games you are as likely to run into a caster as a fighter and as likely to face a save as something that uses an attack roll.

So yeah, let the high AC guys be good at having a high AC. Everyone makes choices and in this case they may have chosen to be proficient in heavy armour over being proficient in dexterity saves; as long as the things that target each of these are equally common then you shouldn't have too much of an issue. You run into problems if your campaign is too focussed on what it targets - if spells and attacks are not distributed evenly between different potential weaknesses then it rewards players for overspecialisation.

[Sigreid]

Rustmonsters.

[DevilMcam]

I don't think the issue is the guy with 22 AC, but the one with 13.

Any character can start the game with 14 AC without sacrificing anything and it takes very little invesment to bump it up to 15 or 16.

As pointed earlier having good AC does not makes you good at protecting people.
But it doesn't hurt to talk a bit with your players :
"Hey guys I can't really have dumb monster focus fire you just because you are wearing plate you know. If you want to protect your friends you should actively work for it. If you Don't know how, I can give you some pointers"

[Misterwhisper]

How about stop trying to punish the players that are doing what their class is supposed to do and cheating them by making their choices and resources useless, you could instead punish the idiot with crap ac.

What is the point of ac if the dm is just going to adjust so you get hit just as much anyway.

This is not an mmo, their is no threat meter.

Stop trying to play mmos in table top. If you can’t protect yourself it is your problem.

Wizards have mage armor and shield. If they still choose to have garbage ac, when they die it is their problem.

[Biffoniacus_Furiou]

Use a mix of strong and weak opponents. You can often just throw in a bunch of weak opponents without noticeably changing the EL of the encounter. Even CR 1/4 Skeletons can be useful in outflanking the party or assisting stronger opponents. The weaker enemies can hit the casters without dealing significant damage, making them a threat. They can use the help action to give stronger opponents advantage on their attack (or grapple/shove attempts) on the tanky characters.

[False God]

I don't really worry about adjusting to hit bonuses to adjust to the party.

I have dumb monsters attack the high AC PCs, which makes them feel good about their choice, but smart monsters try to move around them to attack the wizard if they can, then I let the party try to adjust their tactics.

I don't hide this from my players either. I tell them ahead of time that just like they try to do, tactically proficient monsters will try to take out spell casters first. The wizard should be afraid of combat. They should be hiding and dodging as much as possible.

Basically this. Smart foes make more tactical decisions. Dumb foes don't.

[Sigreid]

How about stop trying to punish the players that are doing what their class is supposed to do and cheating them by making their choices and resources useless, you could instead punish the idiot with crap ac.

What is the point of ac if the dm is just going to adjust so you get hit just as much anyway.

This is not an mmo, their is no threat meter.

Stop trying to play mmos in table top. If you can’t protect yourself it is your problem.

Wizards have mage armor and shield. If they still choose to have garbage ac, when they die it is their problem.

I look at the question a little differently. It's not about negating a character's advantage or coolness. It's about not having a single answer for all challenges. You don't make the high AC useless, you make it not the answer in some percentage of the game.

[Sorinth]

The easiest way is to have them fight creatures that force them to roll saving throws. For example monsters with Breath Weapons force Dex saving throws for damage.

But assuming you don't want to just use monsters that use magic or have abilities that cause paralysis/restrained/stunned conditions then tactically the way to deal with high ac opponent is by gaining advantage on the attack. The easiest way is if you use the Variant flanking rules, the PCs would also benefit from this so maybe just ask/tell the players that you want to test out those rules for a couple sessions. Then decide after seeing them in action whether it's something you guys want to keep or not.

The next best way to achieve advantage is knocking the enemy prone. Ideally you'd establish a grapple, then shove them prone so that they can't stand up unless they break the grapple first. Enemies basically dog pile the prone creature.

And finally there is the attack while hidden. Goblins can BA Hide to attack with advantage every turn much like a Rogue. And pretty much any enemy can use ambushes and hit & run tactics.

[MaxWilson]

I look at the question a little differently. It's not about negating a character's advantage or coolness. It's about not having a single answer for all challenges. You don't make the high AC useless, you make it not the answer in some percentage of the game.

Agreed.

I will add that you should do this even if there aren't any high-AC characters in your game currently. Have some percentage of monsters (25%?) be stuff like Gorgons and Winter Wolves and Bodaks with damage AoEs, another percentage (10%) be monsters with save-based disabling attacks like Yetis, etc. This also helps out balance out stuff like Conjure Animals spam because both AoEs and disabling the spellcaster make the summoned animals go away.

Also don't forget about environmenal effects like traps and falling damage. You could have monsters like Grungs and Githyanki who fight in ways such that to take the fight to them, you do things that either risk falling damage or practically mandate falling damage. (If a monster jumps down a 50' ravine and runs off to get reinforcements, are you going to just let it get away, or take the 5d6 falling damage per PC/summons to pursue, or something in between?)

[GigaGuess]

So...my 2 cents, as I see it:

The party wants to use themselves as walls of plate to protect the squishies, but are getting upset when that doesn't work...that is on them. Like I get the feel-bad of a plan coming together as they desire it to, but it's their failure to strategize, not your failure to accommodate. As has been said, a mindless creature, sure, it'll keep wailing on the wall because it's just gonna zero on a target. Even an unintelligent creature will know a failed effort when it sees one. A wolf might take a few chomps at Mr Plate Mail before wandering to a different target (though possibly granting an AoO.) And an intelligent target WILL strategize. They will prioritize threats, so they will need to improvise their plan on the fly. So I would say impress on them that they may need to try different things. The Wizard might need to get a few more defensive spells.Help them see this not as something that is working against them, but a chance to reevaluate the issue.

Failing that...maybe toss an Elven Chain to the Wizard...?

[Wizard_Lizard]

Let them shine, but a way to make them seem not to OP is to use more saving throw effects.

[tomjon]

Just wait until your paladin gets level 6 and then starts sorcerer. Good times shield blur and hast. Don’t forget that natural 20 and a level 5 smite.

Maybe I miss understood you want high ac right

Don’t worry to much just hand out ac items for the squishies if your really concern about it. Or use the power of flanking pack attack and the like. A steel wall is not the end all. A well placed spell will end an encounter much quicker.

[Jerrykhor]

22AC is high? Those are rookie numbers man.

If all else fails, just throw a demon lord at your players. I heard Demogorgon's attacks has +14 to hit.

[Whit]

Why adjust it? You as the DM decided what they can do and get. Don’t change things just play smart. Most enemies are not dumb.
And what level are they.

[arnin77]

You know what sucks when you have a 22 AC at level 5 with plate mail, a shield, a ring of protection and Defense fighting style? Heat metal.

One thing I did as a DM was to roll dice for each creature to see which PC it wanted to attack. Give your PCs a number on a sheet of paper, then roll a d4 or d6. Maybe all your monsters gang up on the paladin or maybe they gang up on the Wizard. Maybe they go for pcs no one would have expected. Challenge yourself to explain why they are doing it and let your pcs hear you roll for who each monster attacks as you’re explaining what it does. It adds tension to the battle and if the PCs complain at least it’s chance deciding the outcome and I think that’s as fair as it gets.

[HappyDaze]

Don't treat the battle like a game, treat it like a confusing melee with many NPCs having poor intel.

The reason that the monster keeps swinging at the fighter even though there's someone squishy in the back is because there is a big guy in its face with a freaking sword. Unless it is a tactical genius, it does not want that at its back! And it doesn't necessarily know the warrior's AC offhand. Even if the two lead fighters aren't establishing a tactical line that makes it impossible to get past them, as long as they aren't fighting either (a) massive groups that will swarm them and keep going or (b) highly mobile and intelligent tactical enemies, they're going to start by hitting the thing that is right there hitting back.

So let a lot of your monsters not run past the front line, because if they do they're going to be caught between the front line and the squishies. And then let those monsters have a low enough to-hit bonus that a lot of their attacks whiff. And then let the PCs feel good that attacks are whiffing instead of hitting the wizard. And then you have succeeded.

And as an aside: 22 AC is good, but it shouldn't be "monsters can't possibly hit" good. What level are you dealing with? Maybe you should use smaller groups of higher-CR enemies, so that it's easier for the frontline to engage them but also easier for them to do some damage?

*EDIT* Also, multi-attacks. A lot of enemies attack multiple times, which you can use to allow some attacks to whiff but others to hit. For example, a manticore is only CR 3. It can jump the toughest-looking enemy and attack three times; even if each attack only has a 1-in-5 chance of hitting, the chance of something hitting is better than 50/50. A Knight could engage the enemy paladin to cover his allies, while shouting encouragement at the people fighting the Fighter, and leaving a backrow person of his own to fire arrows at the wizard. And so on.

Play the monsters the same way the PCs play their characters. If both sides play it "in-character" with the confusion of melee and the mental states of the combatants in mind, that's great. If both sides play it like a tactical game, that's fine too. Problems come up when one side plays it one way and the other side goes the other direction. It used to be that it was GMs that most risked falling into god-mode gaming with perfect tactical insight, but these days I find that many players switch into this the moment initiative dice are rolled. If that's the case, they are probably looking for the challenge of opponents that do the same.

[DwarfDM]

Mind controll the high AC character and make him fight his buddies while the BBEG sits back and sips wine whilst eating a selection of fine cheeses.

[da newt]

Play your bad guys like they want to live/win based on their lore/abilities. A good resource for this sort of thing is "the monsters know what they're doing." (blog and Book)

Some creatures / enemies ought to try to work around the hard targets to get to the soft ones - some should crash upon the rocky coast that the high AC guys have invested in becoming.

Have fun, and remember this isn't a contest where the DM or PC's win - it's an experience and a puzzle.

[Lupine]

how do you deal with one character getting 22 AC and another having 13?

Saving throws.

You can have AC:2000, and it won’t make a lick of difference if you have 8 DEX, and I ask you to make a DC20 dexterity saving throw.

Notice how most high CR creatures have a recharging saving throw based action that packs a massive punch, and an attack with a large to-hit bonus which deals high, but consistent damage.
And they often have high AC.
The result is that they use the saving throw attacks when they have them, targeting high AC, and focus the lower AC characters with their single target attacks.
Once the easy targets are down, then it goes for the high AC targets.

[Friv]

Play the monsters the same way the PCs play their characters. If both sides play it "in-character" with the confusion of melee and the mental states of the combatants in mind, that's great. If both sides play it like a tactical game, that's fine too. Problems come up when one side plays it one way and the other side goes the other direction. It used to be that it was GMs that most risked falling into god-mode gaming with perfect tactical insight, but these days I find that many players switch into this the moment initiative dice are rolled. If that's the case, they are probably looking for the challenge of opponents that do the same.

The problem with that is that the GM already has information that the PCs lack. When the fight begins, the PCs don't know which monsters are spellcasters, who is squishy, and what the biggest danger is. If an enemy spellcaster tosses a fireball at them, they don't actually know if there are more where that comes from, or if that was the end, especially if the enemy follows up with smaller spells that might not be worth beelining towards.

On the other hand, the GM knows exactly what resources the PCs can bring to bear, whether the mage has invisible armor alongside their death bolts, whether they're coming into the fight tired and low on resources or at full power, and so on. This means that if they start playing it as a tactical game, they're likely to start using information that their NPCs don't have yet.

People saying, "Oh, the bad guys will obviously go for the squishy wizard in the back because squishy wizards do the most damage" - they only do the most damage if they have (a) spells, and (b) spells appropriate to the situation. Plenty of people with robes aren't wizards. Plenty of wizards only have low-level spells, or only have a couple of spells, and once they've cast their opening buffs they're going to be plinking with cantrips.

And in this particular case, the PCs aren't going for good terrain and careful battlefield control, so I assume that even if they want to be doing good tactical stuff, they don't have the heads for it.

[HappyDaze]

The problem with that is that the GM already has information that the PCs lack. When the fight begins, the PCs don't know which monsters are spellcasters, who is squishy, and what the biggest danger is. If an enemy spellcaster tosses a fireball at them, they don't actually know if there are more where that comes from, or if that was the end, especially if the enemy follows up with smaller spells that might not be worth beelining towards.

On the other hand, the GM knows exactly what resources the PCs can bring to bear, whether the mage has invisible armor alongside their death bolts, whether they're coming into the fight tired and low on resources or at full power, and so on. This means that if they start playing it as a tactical game, they're likely to start using information that their NPCs don't have yet.

People saying, "Oh, the bad guys will obviously go for the squishy wizard in the back because squishy wizards do the most damage" - they only do the most damage if they have (a) spells, and (b) spells appropriate to the situation. Plenty of people with robes aren't wizards. Plenty of wizards only have low-level spells, or only have a couple of spells, and once they've cast their opening buffs they're going to be plinking with cantrips.

And in this particular case, the PCs aren't going for good terrain and careful battlefield control, so I assume that even if they want to be doing good tactical stuff, they don't have the heads for it.

It's not a problem; if everyone is having fun, it doesnt matter. Players metagame all the time. Many have practically memorized the Monster Manual regardless of having fresh-eyed PCs. Sure, the DM can go too far with nigh-unlimited metagame knowledge, but that's not the same as playing tactically. A good DM can pull it off and make it look easy because they do their balancing in the prep. DMs that aren't there yet often have to fudge rolls and rebalance on the fly or else risk unsatisfying encounters (either too easy or too hard). There's a lot of pieces to balancing encounters, and Challenge is so badly written that a DM has to learn to go way beyond it. Style of play is a huge factor in balancing encounters (if you don't think so, consider a game where enemies regularly make an attack or two to ensure a 0 hit point enemy stays down), and styles that work for some groups probably look abhorrent to others.

[Tawmis]

In my campaign I've noticed that some of the PC's have gotten their AC's incredibly high. Specifically the fighter and paladin. The easy fix is to give everything a higher to hit bonus, but to make something have a 40% chance of hitting the tin cans, it will have a 100% chance to hit the wizard. The players have communicated a desire to use their high AC to protect the squishy casters, but often fail to establish a tactical position that would allow them to actually defend the back line, and there is no reason for a creature to attack something it can't hit when it can reach targets who make easier prey/victims. I guess I'd just like to hear how other DM's deal with large AC disparities. Because I've noticed frustration when my players are unable to defend the easier targets.
TL DR how do you deal with one character getting 22 AC and another having 13?

Well, the players who have fighter types, should have a high AC. That's their job to get in there and take things head on - while Wizards blast from the back, Rangers blast from the back, Clerics heal (and some can even tank).

Now, the one thing is - yes, technically a Paladin with AC 22 is harder to hit than a Wizard with AC 13. However, the mentality of "why would a monster stand and try to hit a Paladin with AC 22 vs a Wizard with AC 13" sort of slides into "meta gaming" as a DM.

Yes, you as the DM know the Wizard is going to be easier to hit. However, in reality - it's not that a creature is always "missing" when they roll a 16 against the Paladin - it could be thought that the strike hits but doesn't penetrate the Paladin's armor. So the monsters may still be technically "hitting" the Paladin with high rolls, but not doing enough to get past the armor. So for me, not every "miss" is always a "miss" - if a roll comes close to meeting the target AC, I will describe it as a hit - but a hit that doesn't do damage. Sometimes, if it's 1 off, I will even describe it as a hit that forces the Paladin to take a step back from the hard hit that dings/dents his armor, but does no actual damage to him (or her).

Also, a monster turning their back on a heavily armored person with a big sword, does not seem strategically sound either on any battlefield.

Just my two cents.

For all that's worth.

Inflation these days, might not even be worth that! :D

[Mr. Wonderful]

You challenge high AC characters with numbers, restraining attacks, will saves and mobility.

High AC is great, but its part and parcel of the game and requires giving up other bonuses. You can't have it all.

Mix up your bad guys and everyone will get a turn to shine - or fail.

[greenstone]

Give them an escort quest.

*evil laugh*