D&D 5E Armor class and proficiency on saving throws

[daimaru42]

OK, as a rogue, my character has proficiency on dexterity saving throws. Armor class has dex added in. For leather, 11 + his dex modifier. My question is, should I also add in his proficiency. Reasonably, you could say yes, because armor class amounts to a saving throw. Or, you could say no, because no dice are rolled.

First time I've ever played a rogue.

 

[Tormyr]

No, for several reasons.

1. Each method for calculating AC is separate from others and describes everything that goes in it. You have chosen light armor which is the armor's AC + your DEX modifier. Other means of calculating armor (medium armor, heavy armor, no armor, monk, barbarian, mage armor, and draconic sorcerer are all different and exclusive of each other. You choose the best method for your character, but only one method.
2. AC is not a saving throw. It is closer to setting a DC for a saving throw (as AC is essentially a DC of a different sort), but it is calculated in the one of the methods referenced in #1.
3. Your proficiency in DEX saving throws only counts for when you actually roll a DEX saving throw. It does not come into effect at any other time.

 

[rczarnec]

OK, as a rogue, my character has proficiency on dexterity saving throws. Armor class has dex added in. For leather, 11 + his dex modifier. My question is, should I also add in his proficiency. Reasonably, you could say yes, because armor class amounts to a saving throw. Or, you could say no, because no dice are rolled.

First time I've ever played a rogue.

Proficiency bonus does not get added to AC.

 

[Harzel]

Proficiency bonus does not get added to AC.

This is absolutely correct for the rogue PC. But just as a piece of fun trivia, there is one (that I know of) obscure case in which proficiency bonus is added to AC. For a UA ranger / beast conclave, the ranger's companion animal's proficiency bonus (which is the same as the ranger's) is added to its AC. That's not 'official' material, of course, but it is WoTC-generated.

 

[GMMichael]

You should absolutely use dex save proficiency in your AC, because the dexterity save represents your character's ability to avoid physical damage that would ignore his use of armor - it's his dodging and weaving to avoid any direct contact. Sure seems like a skill that would prevent weapon damage to me. What's more: when you make a dex save, it's often because you have just a split second to react. Normal attacks provide much longer reaction/warning times, so you would think that you'd get an even larger proficiency bonus (expertise?) against the much slower normal attacks.

2. AC is not a saving throw. It is closer to setting a DC for a saving throw (as AC is essentially a DC of a different sort), but it is calculated in the one of the methods referenced in #1.

You should absolutely not use dex save proficiency in your AC, because AC is not a saving throw! It is, especially after Bounded Accuracy, a way to differentiate low-level combat from high-level combat. At low levels, AC is what keeps you alive in combat. At high levels, hit points are what keep you alive.

 

[Tony Vargas]

OK, as a rogue, my character has proficiency on dexterity saving throws. Armor class has dex added in. For leather, 11 + his dex modifier. My question is, should I also add in his proficiency. Reasonably, you could say yes, because armor class amounts to a saving throw. Or, you could say no, because no dice are rolled.

No proficiency to AC. Armor class also has armor added in, and it's calibrated without proficiency. The idea is that as the game scales with level your AC doesn't go up much, but your hps (and damage output) balloon dramatically, those many hps represent your ability to avoid damage as you get better at it. FWIW.

Yes, AC is your ability to avoid being hit by weapons (and monsters and, arbitrarily, certain cantrips and a very few spells) and DEX saves are your ability to avoid being hit by all sorts of nasty traps and monster abilities and more than a few spells, but, arbitrarily, very few cantrips. Yeah, they logically be the same thing or darn close to it, but D&D makes them completely different. In 3e, there was a distinction between AC and Touch AC that was along those lines - as well as a 'REF' save, and in 4e there was no "DEX save," but a 'Reflex Defense' that was attacked just like AC & both improved with level like proficiency does in 5e (but faster, way faster).

It might make lots of sense to add proficiency to AC in a variety of ways - proficiency with shield, proficiency with a weapon if you use your reaction to parry a melee attack, proficiency with acrobatics when moving & dodging, etc...
...but 5e is not flexible enough to work that sort of change in without radically re-calibrating all sorts of stuff.

 

[DwynnsPlace]

It might make lots of sense to add proficiency to AC in a variety of ways - proficiency with shield, proficiency with a weapon if you use your reaction to parry a melee attack, proficiency with acrobatics when moving & dodging, etc...
...but 5e is not flexible enough to work that sort of change in without radically re-calibrating all sorts of stuff.[/QUOTE]

OK proficiency can be used for specific skills, abilities, Knowledge, Lore, Equipment and actions like tumble, dodge ect...
Work with your DM and figure out how your character, whom may have purchased Tumble skill twice with proficiency to
gain both the AC Defense bonus vs melee attacks and the AC bonus vs missile attacks or AOE spell attacks. If the DM has
no issues with it and the player wants to pay the cost for it...I say go for it and have fun!

Remember, it's all about having fun!

 

[Croesus]

I suppose one could change the default AC calculation: 10 + Dexterity Modifier + Proficiency bonus. This would pretty much eliminate light armor. It might step on the toes of the monk and barbarian classes, though it could also reduce those classes MAD a bit. It would make the mage armor spell obsolete. Overall, I don't think such a change would be unbalanced, though I'm not sure it's worthwhile.

If, however, the OP is suggesting adding Proficiency bonus to all the standard AC calculations...nope. That would significantly affect bounded accuracy. Characters would miss more often, which would affect enjoyment of the game (the game system assumes a certain accuracy in attacks - that's why hit points are so much higher in this edition). One would also have to re-calculate ACs for most creatures in the MM, which is a lot of work. Overall, I just don't see adding Prof bonus to existing ACs as a good idea.

 

[Tormyr]

I suppose one could change the default AC calculation: 10 + Dexterity Modifier + Proficiency bonus. This would pretty much eliminate light armor. It might step on the toes of the monk and barbarian classes, though it could also reduce those classes MAD a bit. It would make the mage armor spell obsolete. Overall, I don't think such a change would be unbalanced, though I'm not sure it's worthwhile.

If, however, the OP is suggesting adding Proficiency bonus to all the standard AC calculations...nope. That would significantly affect bounded accuracy. Characters would miss more often, which would affect enjoyment of the game (the game system assumes a certain accuracy in attacks - that's why hit points are so much higher in this edition). One would also have to re-calculate ACs for most creatures in the MM, which is a lot of work. Overall, I just don't see adding Prof bonus to existing ACs as a good idea.

I do not think modifying even the unarmored AC calculation is a great idea. A level 17 PC with 20 Dexterity would have an AC of 21 instead of 15. This would make it better than what was attainable by any armor, mage armor, monk AC, Barbarian AC, draconic sorcer AC...basically anything.

 

[Croesus]

I do not think modifying even the unarmored AC calculation is a great idea. A level 17 PC with 20 Dexterity would have an AC of 21 instead of 15. This would make it better than what was attainable by any armor, mage armor, monk AC, Barbarian AC, draconic sorcer AC...basically anything.

Well, a level 17 PC with a 20 Dex having an AC of 21 doesn't really look like a problem to me. At that level, having a good AC is likely common for any character that can afford to put 20 into Dexterity. Heck, a barbarian with 20 Con and 20 Dex has a base AC of 20, regardless of level.

That said, I agree that such a change wouldn't be a good idea. I know my players like hitting often with their attacks, so making things harder to hit will irritate them. Combining lots of hits with lots of hit points seems to be good design in this edition.