Does D&D have any sort of interaction that affects Constitution saves similar to how Evasion affects Dexterity saves?

Question

If I remember correctly, D&D 5e has a class feature for multiple classes called Evasion, where your Dexterity saves prevent all damage on a successful save and still stop half of the damage if you fail your save. Older versions also had this feat for Reflex saves, although I seem to remember it often being a 2-part perk, where only the improved version gave this exact effect, and the base version only does the "save for no damage" effect.

I was wondering if there's officially any effect of the sort for Constitution saves (Fortitude in older editions) in any edition so far from AD&D to 5e – whether it's a class feature, a feat you can buy like that, a magical item, a consumable, a spell,... Anything that's found in an official source, in any of the editions(*). Note that I'm not interested in Wish or any similar "and the kitchen sink" effects.

Reason I'm asking such a broad question: This effect I'm looking for is pretty much what the new COVID vaccines do (they make it so your Constitution saves against the virus nearly completely stop it, and if you do fail your save, you're only mildly affected most of the time), and I was hoping to be able to make a direct comparison to a Constitution save affected by this game mechanic effect rather than having to reference a similar effect for a different type of save.

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(*) If nothing of the sort exists in any editions of D&D, I might be open for suggestions from other systems that have something akin to a Constitution, Fortitude, or Stamina save, and something akin to an effect that makes the save into partial/no damage instead of full/partial damage. If this would make the question too broad for this stack, ignore this note.

Answer 1

The magic item Mizzium Armor (from Guildmasters' Guide to Ravnica, p. 179) works for both Strength and Constitution saves, but only completely reduces half damage to null on a success, so you still take full damage on a failed save.

(It also turns crits into regular hits, as a nifty little bonus.)

Answer 2

D&D 3.5e — “Mettle”

In D&D 3.5e, evasion allowed someone to take no damage on a successful Reflex save against something that usually had halved damage on a successful save. This feature was originally available to monks and rogues, and became available to other classes via supplemental content.

Later in the same edition, additional classes were introduced that had a feature called “mettle,” which worked the same way, except instead of Reflex saves, it worked on both Fortitude and Will saves.

Note that D&D 3.5e only had these three saving throw types—Fortitude based on Constitution, Reflex based on Dexterity, and Will based on Wisdom. There were no saving throws associated with Strength, Intelligence, or Charisma. (These associations were only defaults, however, so special features could and occasionally did change the ability score associated with a given type of save.)

Mettle covered both Fortitude and Will because it was (and, I believe, continues to be, in 5e) relatively rare for those types of saving throws to still have some reduced effect on a successful save. Usually, those kinds of saves just negated whatever the effect was entirely.

To my knowledge, there was no “half-mettle” feature that covered only Fortitude saving throws.

D&D 4e — “Mettle” again

In D&D 4e, we still have Fortitude, Reflex, and Will, but now they are no longer saving throws, they are “defenses” and work the same way that AC does—certain powers had you roll your attack against these defenses instead of AC. (Saving throws were an entirely separate mechanic and there was only the one type, “saving throw.”) Also, Fortitude was based on Strength or Constitution, Reflex was based on Dexterity or Intelligence, and Will was based on Wisdom or Charisma, whichever was higher out of each pair.

But evasion and mettle remained effectively the same—evasion caused attacks that targeted your Reflex to do nothing on a miss, even if they usually did something on a miss, and mettle did likewise for attacks that targeted Fortitude or Will.

D&D 5e — none at the time of writing, I believe

As far as I can tell, D&D 5e didn’t have mettle, or anything similar to it, when this answer was written. It even seemed hard to make in 5e, since Dexterity remains the saving throw associated most strongly with partial or reduced effect on a successful save, but “everything but Dexterity” is now five separate saving throws, instead of just two, which makes having mettle cover all of those seem a fair bit more imbalanced. At any rate, Wizards of the Coast had yet to cover it in their publications.

But anthony taylor’s great answer reports that now they have! So that’s the answer for 5e.

Answer 3

There is no feature that applies just to Constitution saving throws, but Avoidance is a Demilich trait that applies to all saving throws for D&D 5th edition:

If the creature is subject to an effect that allows it to make a saving throw for half damage, it instead takes no damage on a success and half damage on a fail.

KRyan's answer contains answers for the other editions.