Full Plate Mail vs Adamantium Splint Mail

[Douche]

I received adamantium splint mail last week. It's not +1.

Neither is my current plate mail.

So basically, what I'm asking is - for a life cleric, would losing 1 AC be worth becoming immune to critical hits (that's the only effect of adamantium, right?)? I currently have 21 AC (18 from full plate, and a +1 shield)


From a roleplaying perspective, is there anything that I could possibly "reforge" the adamantium into? Perhaps I could just make an adamantium helmet and still be immune to crits? Or would it be more useful as a weapon? What does adamantium do to weapons?

[Oramac]

A crit only has a 5% chance of happening. Personally, unless there's an RP reason for it, or your DM has insane luck rolling crits, I'd stick with the full plate.

AFAIK, there's nothing official about adamantine weapons, but your DM might be willing to work with you on it. Maybe instead of reducing crits (like the armor does), the weapon would allow a crit on a roll of 19 or 20?

[Vogonjeltz]

I received adamantium splint mail last week. It's not +1.

Neither is my current plate mail.

So basically, what I'm asking is - for a life cleric, would losing 1 AC be worth becoming immune to critical hits (that's the only effect of adamantium, right?)? I currently have 21 AC (18 from full plate, and a +1 shield)


From a roleplaying perspective, is there anything that I could possibly "reforge" the adamantium into? Perhaps I could just make an adamantium helmet and still be immune to crits? Or would it be more useful as a weapon? What does adamantium do to weapons?

There are some golems susceptible to Adamantium in the same way as magic weapons. Otherwise, not much

[MaxWilson]

So basically, what I'm asking is - for a life cleric, would losing 1 AC be worth becoming immune to critical hits (that's the only effect of adamantium, right?)?

Well, you'd also be able to punch a golem with your armored fists and still do damage. (They're immune to non-magical, non-adamantium weapons.)

As for reforging: try forging an adamantium helmet and then experimenting with Detect Thoughts/Suggestion/etc. to see if it makes you immune. :)

[N810]

On weapons it gets around damage resistance.
(full damage instead of 1/2 against resistance)

Crit immunity is a pretty good feature,
I like your idea of improving it or forging
it into a helmet of something.

[Dalebert]

On weapons it gets around damage resistance.
(full damage instead of 1/2 against resistance)

Only against a few specific creatures as was pointed out in a recent post, e.g. some golems. It doesn't get around most, e.g. lycanthropes (silver or magic).

[Gurifu]

RAW, Adamantine weapons don't do anything except be harder to break. If you have Smith's Tools and the appropriate Proficiency, or access to a professional smith, you can probably reforge the adamantine armor, but specifics are up to your DM; ask him or her.

For HP tanking, 21 AC is always mathematically better than 20 and crit immunity as long as it's possible for your opponent to roll under 20 on an attack roll, since the 1 extra AC will block a whole hit, while the crit immunity will block damage dice worth less than a whole hit.

If you have lots of Healing to spare, crit immunity gains a little value because it makes it less likely for you to get surprise-KO'd before you can heal yourself back. However, most surprise KOs will come from multiattack, not crits, so I'd still give the 21 AC more value.

[Temperjoke]

Was it a random loot roll? Optimization aside, if you were given it on purpose by the DM then there might be a reason coming that warrants equipping it.

[jas61292]

Unless your opponent gets a bonus on crits, mathematically, higher AC is better if they have a positive ability mod to damage, equivalent if their mod is 0, and worse if it is negative. The former is most likely though.

That said, the bigger benefit of crit immunity is not in average damage reduction, but in the elimination of game changing hits. No one cares that you take less average damage when you are down on the ground from a crit.

Whether or not it is worth it is up to you, but personally, with AC as high as yours, I'd go for the adamantine.

[RickAllison]

There is one advantage to Adamantine Armor that is DM-dependent: being attacked while at 0 HP. It is a small benefit, but removing the automatic criticals of melee weapons from taking two death saves could be very important if your DM ever hits you while you are down. The plate mail is better if you are standing up, but I would rather have the AA if I am down.

Another time when AA would be supreme is not available to you (probably). Every one of the features that saves you from being reduced to 0 HP besides the Long Death Monk has the stipulation that it does not work on a critical hit. So a Shadow Sorcerer, someone who was turned into an intelligent zombie, or a half-Orc would get extra use out of it.

I would wear the Adamantine. Not for the mechanical reasons, but because it is a status thing to have such rare armor and because I prefer the aesthetics of the splint to the plate.

[MaxWilson]

There is one advantage to Adamantine Armor that is DM-dependent: being attacked while at 0 HP. It is a small benefit, but removing the automatic criticals of melee weapons from taking two death saves could be very important if your DM ever hits you while you are down. The plate mail is better if you are standing up, but I would rather have the AA if I am down.

Great point! I hadn't thought of that.


Another time when AA would be supreme is not available to you (probably). Every one of the features that saves you from being reduced to 0 HP besides the Long Death Monk has the stipulation that it does not work on a critical hit. So a Shadow Sorcerer, someone who was turned into an intelligent zombie, or a half-Orc would get extra use out of it.

I don't see that in the half-orc stat block.


Relentless Endurance: When you are reduced to 0 hit points but not killed outright, you can drop to 1 hit point instead. You can’t use this feature again until you finish a long rest.

Nothing about crits there. Here's Death Ward:


The first time the target would drop to 0 hit points as a result of taking damage, the target instead drops to 1 hit point, and the spell ends.

Just sayin'.


I would wear the Adamantine. Not for the mechanical reasons, but because it is a status thing to have such rare armor and because I prefer the aesthetics of the splint to the plate.

Aesthetics are an excellent thing to optimize for, it is true.

[RickAllison]

There is one advantage to Adamantine Armor that is DM-dependent: being attacked while at 0 HP. It is a small benefit, but removing the automatic criticals of melee weapons from taking two death saves could be very important if your DM ever hits you while you are down. The plate mail is better if you are standing up, but I would rather have the AA if I am down.

Another time when AA would be supreme is not available to you (probably). Every one of the features that saves you from being reduced to 0 HP besides the Long Death Monk has the stipulation that it does not work on a critical hit. So a Shadow Sorcerer, someone who was turned into an intelligent zombie, or a half-Orc would get extra use out of it.

I would wear the Adamantine. Not for the mechanical reasons, but because it is a status thing to have such rare armor and because I prefer the aesthetics of the splint to the plate.

[Joe the Rat]

How often are creatures attacking with Advantage? That ups the crit rate significantly.
I'm thinking that the more attack rolls you take, the more likely it is you will face a crit - but I leave it to more statted heads as to if/when/where the balance tips.

[MaxWilson]

How often are creatures attacking with Advantage? That ups the crit rate significantly.
I'm thinking that the more attack rolls you take, the more likely it is you will face a crit - but I leave it to more statted heads as to if/when/where the balance tips.

Conversely, you can become essentially crit-immune by casting the Blur spell. Though as RickAllison points out, that doesn't work when you're making death saves.

[Zman]

Absolutely,make the Adamantine Splint Male over the Full Plate. Mathematically your AC is lower, but the overal damage reduced by avoiding a Critical hits is a larger savings than the +1 AC. Secondly, magical rare armor is just plain cooler than mundane armor.

[Grod_The_Giant]

but in the elimination of game changing hits.
Game changing? Crits, when they happen, are a pathetic handful of extra damage. They're barely worth noting.

[jas61292]

Game changing? Crits, when they happen, are a pathetic handful of extra damage. They're barely worth noting.

Not when a crit knocks you out in a situation you otherwise would have been ok.

Or in any situation where the number of dice is high, like a sneak attack or smite.

Sure, if it is against a standard human doing 1d8+2, it's not so bad. But that is not always the case.

[RickAllison]

Not when a crit knocks you out in a situation you otherwise would have been ok.

Or in any situation where the number of dice is high, like a sneak attack or smite.

Sure, if it is against a standard human doing 1d8+2, it's not so bad. But that is not always the case.

Oooo, let's look at some examples!

The Solar's critical hits can deal an average 41 extra damage, almost doubling his damage. Balor longsword attacks can deal an average 52 extra damage with a critical. However, these are the tough boogers, and aren't really representative of the rest.

Let's look at some lower-CR creatures. A pattern emerges that the ability becomes more useful with larger creatures that dole out more damage dice. The bulette deals almost all of its damage with the criticals, as does the giant elk. A sprite hand next to nothing.

[Rainbownaga]

As a primary healer, spike damage is probably more important than peak damage. An attack that drops you to 1hp is fairly easy to recover from, but unless you have a good secondary healer, being dropped to 0 (or potentially insta-killed) would be a serious issue.

[Temperjoke]

I wonder if you could reforge and combine the two armors? Turn the Adamantium into plates and integrate it into your armor?

[Siosilvar]

I'm with everybody who likes the splint mail. Mathematically it's less effective on average, but taking away damage spikes makes your life a lot easier to plan. The extra consistency is a benefit that the pure average doesn't take into account.

[SharkForce]

adamantine will also be better if you're ever paralyzed, just as another factor to consider.

[EKruze]

I believe Crit Immunity beats +1 AC.

+1 AC causes 5% of all swings against you to miss and prevents [Weapon Dice] + [Ability Mod] damage.

Crit immunity kicks in 5% of the time and saves you [Weapon Dice] points of damage.

Technically speaking the +1 AC mitigates more damage, about 3-5 points out of every 20 swings, but Crit Immunity serves to mitigate damage specifically when you need mitigation the most. Of all attacks it's going to be crits that are most likely to put you out of commission altogether, and under most circumstances that's worth the slight decrease in total damage mitigation.

Some attacks will have special riders that deal more damage on a Crit and so Crit Immunity will serve you better there, but then again there are attacks which apply status effects such as Retrain on a hit and in those cases the better avoidance of +1 AC shines through. It obviously depends on what you're fighting, but I'd consider these circumstances a wash.

Other posters have pointed out that if you have some way to impose a consistent disadvantage on your attackers, such as the Blur spell, that this significantly changes the math to improve the value of a +1 to your AC. This is balanced by the fact that if your foe has some means of gaining advantage on you that the +1 AC will be less meaningful while the mitigation of Crit Immunity will increase. This effect is especially noticeable in the case of the Paralyzed condition. This dynamic gets back to the point I was making earlier which is that Crit Immunity is much more likely to save your life than +1 AC. If you have some means of imposing constant disadvantage then you're ahead of the game anyway and total mitigation should mean less to you. If your opponent has you in a tight spot and he has a consistent means of gaining advantage on you then mitigation is more valuable. AC helps you more overall, but Crit Immunity protects you when you need the protection.

[Zman]

Do you like concentration spells???

Negating Crits means your Con Saves are less likely to be half damage saves and more likely to be DC10s. Basically, you won't get hit for massive damage and lose concentration because of the high Concentration Save DC.

[SharkForce]

it's worth noting that +1 AC may not help you against a crit, but it *could* save you from that crit being a life-threatening situation.

anyways, in 5e it's pretty close. if you could get enough stuff to stack your AC to be nearly unhittable, i'd rate the +1 AC much higher, but as it stands they're pretty equal.

note: +1 AC will be relevant 5% of the time, but it is *not* a 5% decrease in damage taken (nor is critical hit immunity, for that matter). in 5e it is more likely somewhere around 10% less damage taken, against most enemies, depending on their attack bonus and your AC; if they hit you only on a 19 or 20, +1 AC would mean you're taking somewhere around 1/3 the damage you would otherwise, and since your HP likely account for enough to take 2-3 crits would also do a lot to protect against the spike damage people are talking about also.

[MeeposFire]

it's worth noting that +1 AC may not help you against a crit, but it *could* save you from that crit being a life-threatening situation.

anyways, in 5e it's pretty close. if you could get enough stuff to stack your AC to be nearly unhittable, i'd rate the +1 AC much higher, but as it stands they're pretty equal.

note: +1 AC will be relevant 5% of the time, but it is *not* a 5% decrease in damage taken (nor is critical hit immunity, for that matter). in 5e it is more likely somewhere around 10% less damage taken, against most enemies, depending on their attack bonus and your AC; if they hit you only on a 19 or 20, +1 AC would mean you're taking somewhere around 1/3 the damage you would otherwise, and since your HP likely account for enough to take 2-3 crits would also do a lot to protect against the spike damage people are talking about also.

Oddly depending on the exact damage numbers even in that situation the crit immunity may actually be better. As your AC goes up the damage on your critical hits (which some people forget to include in their DPR calculations) it essentially becomes a bigger portion of your average damage. If you get hit on a 2 the critical hit is only a small amount of the average since you would have 90% of your full damage on the calculation with a 5% miss and 5% critical damage but if you get hit only on a 19 or 20 then you only get hit on two numbers but while the crit is 50% of the hits it is actually more than 50% of the damage overall since that hits is a bigger number than the other. SO if your Crit is a large enough even in a high AC situation the crit immunity may help more.

[djreynolds]

Is there another team member who can wear it?

Splint is medium armor, so a ranger or barbarian could use it.

[Arkhios]

Is there another team member who can wear it?

Splint is medium armor, so a ranger or barbarian could use it.

Not in 5th edition, it isn't.

Heavy Armors include:
Ring mail (AC 14, no dex, Str minimum: none)
Chain mail (AC 16, no dex, Str minimum: 13)
Splint (AC 17, no dex, Str minimum: 15)
Plate (AC 18, no dex, Str minimum: 15)

[MaxWilson]

Oddly depending on the exact damage numbers even in that situation the crit immunity may actually be better. As your AC goes up the damage on your critical hits (which some people forget to include in their DPR calculations) it essentially becomes a bigger portion of your average damage. If you get hit on a 2 the critical hit is only a small amount of the average since you would have 90% of your full damage on the calculation with a 5% miss and 5% critical damage but if you get hit only on a 19 or 20 then you only get hit on two numbers but while the crit is 50% of the hits it is actually more than 50% of the damage overall since that hits is a bigger number than the other. SO if your Crit is a large enough even in a high AC situation the crit immunity may help more.

You're forgetting that the adamantium armor is one AC lower. If you get hit on a 19 or 20 with the adamantium splint, you'll get hit only on a 20 with the full plate. Turning a hit into a miss saves you more damage than turning a crit into a regular hit.

[djreynolds]

Not in 5th edition, it isn't.

Heavy Armors include:
Ring mail (AC 14, no dex, Str minimum: none)
Chain mail (AC 16, no dex, Str minimum: 13)
Splint (AC 17, no dex, Str minimum: 15)
Plate (AC 18, no dex, Str minimum: 15)

Well then its a good question. How valuable is that +1 AC? How valuable is defensive style also? How much are you targeted as a cleric? My life cleric is targeted quite a bit, especially when I throw up spirit guardians or drop a big heal... drives the DM crazy.

Lets look at it this way, if you are in melee a lot and you con saves are low and you are at risk because you are facing ghouls and others that can paralyze you... I'd wear the adamantium armor. If your fighter has a low wisdom save and the DM is always casting hold person on him then give him the adamantium.

I got my butt whooped by ghouls on 3 occasions and paralyzed by failing con saves I wasn't proficient in yet.

So who is your party is most at risk for falling saves that lead to conditions that allow auto-crits.

[MeeposFire]

You're forgetting that the adamantium armor is one AC lower. If you get hit on a 19 or 20 with the adamantium splint, you'll get hit only on a 20 with the full plate. Turning a hit into a miss saves you more damage than turning a crit into a regular hit.

It would depend on the exact numbers though generally you would be right. If you were to take 5 damage on a regular hit and 15 damage on a crit the plate would cut you down to 15 damage criticals only while andamantine would have you get hit by a 2 instances of 5 damage each then the andamantine would be better.

However I do realize that would be quite rare and would require fighting enemies that do extra damage on a critical and not just double damage. Spells would come about even in this case since they usually only deal dice in damage with no mods. Most weapons would have mods which would swing it towards plate the higher the mods get in relation to everything else.

For instance the way many people talk about how paladins would be used would probably want to use andamantine armor since many advocate using smites on a crit. IN that case all those extra dice and having all of them doubled (and then ignoring all the doubled damage) may very well overwhelm the extra miss generated by higher AC. Once again though this would be a rare case and also relies on particular play style for a specific class.

[JellyPooga]

Is your next mission going to be against a thieves guild that has a thriving pit fighting business? If you're going up against a bunch of Rogues (or worse Rogue/Champion Fighters), or other baddies that get more out of crits (hobgoblins come to mind), then wear the adamantine.

Keep both; put the one you're not wearing on a manikin in your mansion. Haven't got a mansion? In that case sell both sets of armour, go buy yourself some property and wear something cheaper! Living comfortably is definitely preferable to a marginal increase in survivability...

[Pope Scarface]

As a healer, you should take the adamantine, because it protects you from the auto-crit from an Assassinate, and the healer is the most likely member of the group to be tagged with that.

[Socratov]

I'd like to point out that immunity to crits also means immunity to the Vorpal Sword or its ilk.

[RickAllison]

I'd like to point out that immunity to crits also means immunity to the Vorpal Sword or its ilk.

This is a common misconception, and incorrect. The Vorpal Sword and Sword of Sharpness rely on rolling a 20 rather than scoring a cortical. Otherwise, Hold Person, Champions, and Assassins would become disproportionately powerful.

[Pex]

No matter what your AC is, you're going to get hit. The better the AC obviously the less often you are hit, but you're going to get hit. Striving to get a high AC as possible is fine, but at some subjective point your AC will be high enough. You can never reach a point where you're never hit, so one more AC point isn't going to be a difference.

Take the Adamantine armor. Being immune to critical hits is supreme. While there's never a good time to be critically hit, sometimes it happens at the most inopportune time. Being immune to that particular instance of massive damage is so worth it.

[Blarmb]

What kills you is spike damage. I'd take the crit immunity, personally.

[MaxWilson]

No matter what your AC is, you're going to get hit. The better the AC obviously the less often you are hit, but you're going to get hit. Striving to get a high AC as possible is fine, but at some subjective point your AC will be high enough. You can never reach a point where you're never hit, so one more AC point isn't going to be a difference.

That's an odd way of looking at it--as if round by round timescales are the only things that matter.

If AC 19 means you can kill a dozen orcs but take 100 points of damage in the process, and AC 20 means you can kill a dozen orcs but take 82 points of damage in the process, that's a measurable increase in capability. (I made those numbers up but they should be in the right ballpark.) Could be relevant.

[SharkForce]

again, +1 AC doesn't prevent crits, but it does make it less likely that when a crit happens it will be at a particularly bad time (because you often won't have taken as much damage, and therefore have the HP remaining to absorb the crit without getting KO'd).

generally speaking, +1 AC will be better on average most of the time, but you'll be *really* happy you're wearing adamantine if you get into a situation where automatic critical hits can happen or similar (for the record, +1 AC is still arguably better even against rogues other than assassins that get to use their assassinate ability, because it is still negating an entire hit which is sneak attack damage + weapon damage + attribute, while preventing a crit only prevents the doubling of sneak attack damage + weapon damage, thus tilting the scales very slightly in favour of +1 AC by the amount of attribute damage you would have taken... on average. obviously, which one actually turns out better depends on the actual rolls in a given combat. either bonus could do nothing or prevent huge amounts of damage).

so, both have their uses. +1 AC is usually slightly better, but adamantine is almost as good in most situations and much better in a few situations. the frequency of those situations will determine whether you want adamantine splint or regular full plate. if those situations almost never come up, you want full plate. if they come up frequently, you want adamantine. somewhere in the middle... harder to say. i'd give a slight edge to adamantine because it can help you survive in a worst-case scenario (not so much the random crits, it's the paralyzed or otherwise getting auto-crit situations i'm thinking of), but they really are very close.

of course, better yet would be to find a way to use the adamantine from the splint mail and get a suit of adamantine full plate ;)

[jas61292]

again, +1 AC doesn't prevent crits, but it does make it less likely that when a crit happens it will be at a particularly bad time (because you often won't have taken as much damage, and therefore have the HP remaining to absorb the crit without getting KO'd).

generally speaking, +1 AC will be better on average most of the time, but you'll be *really* happy you're wearing adamantine if you get into a situation where automatic critical hits can happen or similar (for the record, +1 AC is still arguably better even against rogues other than assassins that get to use their assassinate ability, because it is still negating an entire hit which is sneak attack damage + weapon damage + attribute, while preventing a crit only prevents the doubling of sneak attack damage + weapon damage, thus tilting the scales very slightly in favour of +1 AC by the amount of attribute damage you would have taken... on average. obviously, which one actually turns out better depends on the actual rolls in a given combat. either bonus could do nothing or prevent huge amounts of damage).

so, both have their uses. +1 AC is usually slightly better, but adamantine is almost as good in most situations and much better in a few situations. the frequency of those situations will determine whether you want adamantine splint or regular full plate. if those situations almost never come up, you want full plate. if they come up frequently, you want adamantine. somewhere in the middle... harder to say. i'd give a slight edge to adamantine because it can help you survive in a worst-case scenario (not so much the random crits, it's the paralyzed or otherwise getting auto-crit situations i'm thinking of), but they really are very close.

of course, better yet would be to find a way to use the adamantine from the splint mail and get a suit of adamantine full plate ;)

Ultimately, its statistics vs strategy. While there are obviously exceptions both ways (rider effects on hits / brutal crits), in general, the +1 AC is statistically better, on average. That said, it is better by an almost negligible amount. It saves you your opponents ability modifier every one out of 20 attacks. That's not a lot. But, it certainly is something, and in the long run, it really helps keep damage down.

What Adamantine provides you with is consistency and predictability. You can't plan for a crit, and while even with a sneak attacking rogue, +1 AC saves you more damage on average, it is much harder to adapt when you just took an extra 5d6 damage unexpectedly and dropped.

Both have advantages and disadvantages, and while usually I'd consider the Adamantine far more valuable, both have their place.

[Pex]

I'm wondering if the DM did this on purpose for personal amusement. Since both options are equivalently good they're balanced with respect to each other. The player gets a nice benefit either way, so it's win-win all around. The fun is just in watching the agonizing decision making.

:smallyuk:

[SharkForce]

Ultimately, its statistics vs strategy. While there are obviously exceptions both ways (rider effects on hits / brutal crits), in general, the +1 AC is statistically better, on average. That said, it is better by an almost negligible amount. It saves you your opponents ability modifier every one out of 20 attacks. That's not a lot. But, it certainly is something, and in the long run, it really helps keep damage down.

What Adamantine provides you with is consistency and predictability. You can't plan for a crit, and while even with a sneak attacking rogue, +1 AC saves you more damage on average, it is much harder to adapt when you just took an extra 5d6 damage unexpectedly and dropped.

Both have advantages and disadvantages, and while usually I'd consider the Adamantine far more valuable, both have their place.

how is it that you believe you can plan for getting hit more often but not for critical hits? i mean, i dunno about you, but i have no more ability to control whether the DM hits me in a round by a 1 point margin than i do the ability to prevent critical hits. all that needs to happen is i get hit one time more often in a round because of having 1 less point of AC, and suddenly that devastating spike damage is quite frequently going to still be there. the difference between a monster with two attacks hitting twice vs once (or three times vs twice vs a monster with three attacks, and so on) is very much like the difference between getting critically hit and not getting critically hit.

(also, on-hit effects are a lot more common than brutal critical effects, and can certainly very easily lead to taking a lot more damage as well).

spike damage can happen whether you have adamantine armour or not.

[jas61292]

how is it that you believe you can plan for getting hit more often but not for critical hits? i mean, i dunno about you, but i have no more ability to control whether the DM hits me in a round by a 1 point margin than i do the ability to prevent critical hits. all that needs to happen is i get hit one time more often in a round because of having 1 less point of AC, and suddenly that devastating spike damage is quite frequently going to still be there. the difference between a monster with two attacks hitting twice vs once (or three times vs twice vs a monster with three attacks, and so on) is very much like the difference between getting critically hit and not getting critically hit.

(also, on-hit effects are a lot more common than brutal critical effects, and can certainly very easily lead to taking a lot more damage as well).

spike damage can happen whether you have adamantine armour or not.

The idea is that its easier to plan the smaller the potential range of damage you will be taking is. The amount of attacks aimed at you either way will be the same, and while the average damage that the +1 armor guy takes is lower, the potential range of damage they can take is higher. This allows you to wade into combat with more confidence at a lower HP.

[SharkForce]

The idea is that its easier to plan the smaller the potential range of damage you will be taking is. The amount of attacks aimed at you either way will be the same, and while the average damage that the +1 armor guy takes is lower, the potential range of damage they can take is higher. This allows you to wade into combat with more confidence at a lower HP.

and +1 AC lets you wade into combat less likely to be at lower HP in the first place...

[RickAllison]

and +1 AC lets you wade into combat less likely to be at lower HP in the first place...

Think of it statistically. The damage between the two is slightly in favor of the +1 AC, but not by much. For any given set, the difference in the expected damage is 0.05*(XdY+Z) versus 0.05*(XdY). However, the maximum damage possible changes significantly between the two. Let's look at a Young Red Dragon's Multiattack to see the difference:

One bite (2d10+1d6+6) and two claws (2d6+6), +10 to-hit. The expected damage (no shield) is 31.65 for plate and 32.55 for the AA. The maximum damage, however, ranges from 4d10+6d6+18 for the plate to 2d10+3d6+18, a difference of 21.5 average, which is a significant chunk of change for any combatant.

Of course, that assumes the enemy has neither disadvantage nor advantage. If the enemy is likely to have advantage. The weight given to criticals almost doubles (.0975 as opposed to .05). Meanwhile, the +1 AC from the plate means less and less as to-hit rises with the advantage. On the flip side, the ability to give enemies disadvantage greatly weighs the difference toward the plate armor (as the likelihood of a 20 drops to the low-low .0025). A cleric, unfortunately, doesn't have many options for that.

[djreynolds]

Here is a question, RAW. If say I am the victim of a ghoul attack and I'm paralyzed and any hit is an auto-crit, does adamantium armor still protect me from these auto-crits or does the condition trump this no matter what?

[MaxWilson]

Here is a question, RAW. If say I am the victim of a ghoul attack and I'm paralyzed and any hit is an auto-crit, does adamantium armor still protect me from these auto-crits or does the condition trump this no matter what?

I'd say the armor protects you.

[djreynolds]

I'd say the armor protects you.

Then its a reason to use the armor, if say you are a cleric with a crappy con save and you haven't taken resilient con or a fighter with a bad wisdom save. These two would benefit from the armor. Auto-crit hurts

Just recently in CoS, Baba Lysga Power Word stunned my cleric, and the hut auto-crit me for 55 or 60. My life cleric was out of the fight for a good 5 rounds till someone could heal me.

[SharkForce]

armour prevents crit. the general rule is that paralysis allows crits. the specific rule of adamantine armour overrules the general rule.

[Douche]

I should probably mention that the DM for this game seems to extraordinarily score a lot of crits...... Particularly when we are doing very well in combat and have expended very few resources. And he rolls behind a screen. But it's probably a good thing I didn't mention that, cuz it would've painted your opinions a certain way.

In other words, he's a good DM but I'm pretty sure he cheats when we are breezing through an encounter and he wants to raise the tension a bit/burn our resources a little more.

So, verdict: after weighing all your responses, I'm going to go with the adamantium armor.

[RSP]

Technically according to RAW, the Adamantine could actually make you unhittable if you can get your AC up high enough using other means (def fighting style, ring of pretection, def duelist, etc).

"If the d20 roll for an attack is a 20, the attack hits regardless of any modi ers or the target’s AC. This is called a critical hit, which is explained later in this chapter."

Since, RAW, a Crit is what makes a 20 autohit, Adamantine armor would mean the autohit feature no longer works.

Granted, you would still need an AC in the 20s and still it would only work against attackers with low attack bonuses but it's something to consider.

[MeeposFire]

Technically according to RAW, the Adamantine could actually make you unhittable if you can get your AC up high enough using other means (def fighting style, ring of pretection, def duelist, etc).

"If the d20 roll for an attack is a 20, the attack hits regardless of any modi ers or the target’s AC. This is called a critical hit, which is explained later in this chapter."

Since, RAW, a Crit is what makes a 20 autohit, Adamantine armor would mean the autohit feature no longer works.

Granted, you would still need an AC in the 20s and still it would only work against attackers with low attack bonuses but it's something to consider.

Unless they changed the exact wording I recall it saying that it was "also a critical hit" which implies that the auto hit was actually separate from the critical part.

[RSP]

The quote I put up is straight from the free online version of the rules. I didn't check it against the most recent erratas but I'm assuming they would have updated the free pdf. If anyone has it errata'd, please post (I'm afb at the moment).

[RickAllison]

I think part of the reason of the change was they realized that it did not create loopholes with paralyzation (they have to hit before it became a critical hit), but it made the Champion's improved critical feature function improperly.

[RSP]

ah, the rule is in the Adamantine: Crit becomes regular hit, so cannot avoid autohits. Just in case anyone was going off my previous post.

[Alerad]

Save for the ability score bonus damage to hits, +1 AC or no crits are almost the same.
(Example: Enemy who deals 1d8+5 damage on hit will hit for for 5 more damage every 20th attack if you wear the Adamantine armor. That's a 5 * 0.05 = 0.25 more damage per hit over the full plate).

If that worries you, go for full plate. I would personally take the Adamantine splint mail, as an unexpected crit can deals close to double damage in one blow, which can render you unconscious more easily.

Otherwise consider that wil lower AC you will get hit 1/20th more often, which also increases the chance of losing a Concentration spell. If you have Shield/Parry/Other ability which can raise your AC on demand, definitely go for adamantine.

[Plaguescarred]

+1 AC is more advantageous overall than crit canceling so i'd stick with the plate armor.

[Arkhios]

If you're frequently on the line of getting your face beaten with whatever sticks, there's overall higher chance of being critically hit; +1 to AC doesn't help much there because a Critical Hit always hits, no matter your total AC, so in the end it's irrelevant if your AC was 19 or 20 (or even higher). In this case, seriously, Adamantium Splint is better than Plate armor. It's more about not taking huge amounts of damage from single hit and less about being hit more often.

However, if you're not constantly under beating, higher AC might save the day for you, because if you're attacked less frequently, that high AC makes you less likely to being hit (obviously), and you might survive even a critical hit because your total hit points are behind the safety of your position: not being attacked as often as someone else. Less attacks vs high AC = less chance being hit. Also, as before, if you take a critical hit, your overall AC doesn't matter. But, since you're not taking damage on regular basis, you can quite possibly shake that crit off nevertheless since ideally you have more hit points left to spare.