D&D 5E Touch AC in 5E

[CleverNickName]

I'm playing around with the idea of adding back the Touch AC mechanic from 3.X Edition. Not as a global change (at least, not at the moment) but rather as a special ability of a certain monster. This creature uses an attack that needs only to touch a target, and it doesn't matter whether this touch penetrates the target's armor or not. In fact, it's even better if the attack only hits the armor or shield of its target. Think "rust monster," but worse.

Has anyone done something similar in their games? How did you rule it? (I was going to go with something akin to TAC = 10 + Dex mod, just like in the days of yore, but I'm open to new suggestions.) And if you did this, how did it work? Was it as game-breakingly terrible as I imagine some folks will say? Or was it as laughably inconsequential as I imagine others will say?

Like I said, I'm only planning on implementing this as a single monster's attack ability. But if I like it, I might try to integrate it further.

 

[MarkB]

I'd probably go with something a little simplified - like, if the creature misses on its attack by a margin of, say, 3 or less, it hits the armour and has a different effect. That doesn't require the player to track a separate Touch AC.

 

[Tales and Chronicles]

I'd personally make it a Dex save against a DC of 10 + attack's mod, to keep in theme with the idea of dodging an attack that needs only touch to inflict an effect.

Or yeah, if you want to keep it as an ''attacker rolls'' thing, attack roll against 10 + dex might be the easiest way of doing it.

 

[humble minion]

The devil will be in the special cases. As it's a monster ability rather than a general mechanic, that cuts down a lot of the permutations, but there's still a few you want to think about. Mage armour? A monk's Wisdom bonus to AC? An unarmoured barbarian's Con bonus to AC? Shield of faith?

 

[Don Durito]

The problem with Touch AC is the notion that your level 12 Fighter with a Sword in his hand which he is exceptionally good at but with Dex 10 (Cos Heavy Armour) can't actually defend himself with any competence.

 

[Zaukrie]

The problem with Touch AC is the notion that your level 12 Fighter with a Sword in his hand which he is exceptionally good at but with Dex 10 (Cos Heavy Armour) can't actually defend himself with any competence.

Isn't that a feature of touch attacks, not a problem?

 

[Zaukrie]

I'd personally make it a Dex save against a DC of 10 + attack's mod, to keep in theme with the idea of dodging an attack that needs only touch to inflict an effect.

Or yeah, if you want to keep it as an ''attacker rolls'' thing, attack roll against 10 + dex might be the easiest way of doing it.

I agree with this kind of approach. Dex save. Or the second way.

 

[Hriston]

I think touching a shield is a different question than touching the person wielding it, since the idea of a shield is to put it in the way of an attack. I would say the "attack DC" to hit (touch) the shield is 10 plus any bonus from cover. To touch the person, I would say the DC is 10 + cover bonus + shield bonus + Dex mod.

 

[Stalker0]

I think dex save is the most 5eish way to mimic a touch attack

 

[Don Durito]

Isn't that a feature of touch attacks, not a problem?

How is drawing attention to a point where the system breaks down a feature?

It seems obvious to me that it should be harder to touch a Highly trained Fighter than a peasant - and it should be even harder if that Fighter is holding a great big sharp piece of steel in his hand which he is an expert in using.

(At the very least Touch attacks ought to have disadvantage against armed opponents).