Armor Class against CR 20+ creatures

[Bumamgar]

Looking at creatures with a CR of 20+, the attack mods tend to be in the range of +36 or so.

A 20th level halfling rogue in Mithril Chain shirt +5, Ring of Protection +5, Amulet of Natural Armor 5, wielding a Heavy Shield +5 and a Dex of 22 has an AC of 42. This means the creature will hit on a 6 or better. A human warrior in full plate +5 and everything else the same would also be at a 42.

Are there other, non-epic, ways to boost AC? Clearly damage reduction will help against the inevitable hits, and a cloak of displacement adds a 50% miss chance, but it seems to me that character AC caps at 42 pre-epic, where as challenging monsters have attack bonuses of 36+. Is AC meaningless at high levels, or have I missed a way to boost it higher?

Of course, with Dodge, the rogue could have an AC of 43, and with mobility, and AC of 47 vs. attacks of opportunity, but that doesn't help against a normal attack.

What am I missing? Or is it just that at high levels, you can count on the monsters hitting nearly every swing?

Thank you.

 

[domino]

I don't know that hitting on a 6 or better is "nearly every swing."

 

[Legildur]

Once you start looking at iterative attacks, or attempting to use Power Attack, then the odds start to shift.

You've already identified that displacement/concealement effects assist in avoiding attacks in the first place. There are other tactics that would assist.

Now, what you also need to consider is that AC 42 is not necessarily that high. There are numerous optimzation threads around (particularly on the WotC boards) that generate really high ACs - around 60-100 for non-epic characters.

And now you start to see the value in Feats like Dodge, Combat Expertise, Improved Combat Expertise (CW), Titan Fighting (RoS), and various new abilities for Fighters in PHB II.

 

[Eva of Sirrion]

If you have some resourceful spellcasters in the group, they can try their hands at crafting items that give other types of bonuses to AC (insight, sacred, etc.). But otherwise at this level you can generally count on the first attack belting you unless you have some other type of defense available. But after that, the attack bonus drops by 5 for each attack. Suddenly your foe needs an 11 to hit. In most cases your tank guys need some kind of DR or miss chance or a big HP total to let them weather the first attack, and then they can shrug off the rest of the foe's iterative attacks (assuming the foe can take a full attack).

So to answer your question, if you're just counting on AC to protect you, yeah you're looking at a better-than-average chance that you're gonna get hit by the foe's first attack. But the guys who are supposed to be in melee have the HP to survive one measley attack. If that halfling rogue finds himself in melee he probably did something wrong. DR and miss chances become your friends at higher levels.

 

[argo]

Combat Expertise (+5)
Fighting Defensevly (+3 w/5 ranks in Tumble)
Tower Shield (+2 over heavy shield and portable cover)

Thats another +10 for the human warrior at a cost of -11 to hit

A defending weapon can add another +5 to AC.

And at higher levels some kind of magic item that adds a miss chance, like the aforementioned cloak of displacement, really ought to be standard.

Also keep in mind that at higher levels AC really isn't there to protec you from the primary attack. It is to protect you from itterative attacks and power attacks.

Hope that helps.

 

[the Jester]

In general, it's hard to build a pc that a high-CR baddie can't hit (if the bad guy is a bruiser type of comparable CR to pc level).

There are other ways, of course, and several people have suggested them already. I'd add various spells that buff your AC, potentially (depending on how the dm rules on this particular issue) a second defending weapon.

Also, reconsider your halfling; instead of a chain shirt, substitute bracers of armor +8. Then start with a dex 20 at 1st level, add 5 for level advances, add +6 gloves of dexterity and a manual of quickness of action +5 and you have a dex 36 and an overall AC 49.

 

[Particle_Man]

The feat Elusive Target (CW) is your friend. If you get flanked, your dodge buddy's first attack is vs. the flanker, not you. If your AC can suck up the secondary attacks, you are doing rather well. Mind you, the flanker might slap you around.

 

[frankthedm]

In general, it's hard to build a pc that a high-CR baddie can't hit (if the bad guy is a bruiser type of comparable CR to pc level).

It can be argured that is intentional and expected by the game designers. D&D is a game of scaling HP and exchanging multiple hits until one side is defeated, not completely avoiding hits until the lucky blow lands like Stormbringer, World Of Darkness and other games where capability degrades as you suffer wounds and injury swiftly leads to death.

 

[NexH]

You shouldn't aim for an unhitable AC.
As Legildur said, Armor Class isn't meaningless at epic levels, far from it: if an enemy can always hit you, he will start to use fighting defensively, combat expertise, and power attack, in a measure depending on how low your AC is.

 

[Nail]

You shouldn't aim for an unhitable AC.

Nonsense.

Try Sacred, Insight, and Luck bonuses to AC. That'll put you back into the "practically unhittable" range.