Static "players can't gain life" seems interesting, though I'm not sure I want the effect at common with all of the lifegain in the set (or maybe I do?). Since Rebels are designed to be more aggressive, I'd like if this had an ability that made it more aggressive if it was legendary.

Indeed, IMO this could give aggro almost a controllish angle (ie. more "intelligent") against decks with lots of life gain. It can also be a real decision whether to play the second copy if there's a possibility that the opponent is holding a copy of Resounding Delight in their hand.

I also like that both of those abilities could be considered drawbacks in some cases, which doesn't make the distinguished version strictly better.

As for going/being more aggressive rebel when legendary, I think Spiteful Heir does that well enough already.

The flavor of the whole thing came quite beautifully together if I may say so myself. Disillusioned bride can't be "enchanted" no longer nor gain life - and maybe she's bitter to the extent that she doesn't allow others to do so - and she won't truly be a bride if she isn't legendary (the only one). The rebel type functions mechanically and flavorfully as well. Quite tasteful. :D

Ahh, that's a good point about neither ability being strictly downside/upside. The main concern I had was with lifegain-centric decks, removing one of these just to have another come on the field the next turn is pretty feel bad; given the smaller set size, a dedicated drafter is almost certainly going to have at least 1, most likely 2, possibly 3 of these.

Lifegain kinda sucks normally; hosing it seems like you're shooting your set in the foot.

I agree it's an interesting ability though.

Another point I forgot mention is that I like distinguished here as having multiple creatures with "players can't gain life" would be quite redundant.
Somewhat similarly, distinguished is nice with Fair-One of Minyar since, at least in common, "gain 4+ life per enchantment you cast" could get oppressive.

"Players can't gain life" isn't interesting in that of itself, but at common it's unheard of so I can't for sure predict how it will play out. Hopefully that's something that little playtesting will bring light to.
At the moment, the set is missing any "traditional" burn reach in - though Dejection, Child of Melkor, Fire-Ridden End are capable of that even if they are somewhat unconventional. Also, you could go rakdos for Feed the Emptiness. In any case, I'm speculating that Estranged Bride could give you (another) way to "seal the deal".

"Players can't gain life" really isn't an effect for a Common.

Yeah, but it could it be? After all, this is 'virtually legendary' so some spiciness is to be expected.

No.

You can break some rules, but you're breaking too many. And when you turn a rare into a common, it just isn't right.

Try "damage can't be prevented" instead. That's an uncommon effect. That's a smaller jump and I think is bridged well by the legendary effect.

You really have to start questioning things. What would happen if this were a common? Would it break the environment? If not, why would it be a problem to make it a common?
And most importantly, is "can't gain life effects are always rare" even a 'design rule' at all or just something that for whatever reason hasn't been done yet? You should really think of them more as design 'tips' or 'guidelines' instead of 'rules' btw.

I've reasons to believe that this card would increase interactivity in the set without being oppressive, so I think having it here would be a nice idea.

I don't think there's a single card in the set that prevents damage, so that "damage can't be prevented" would make no sense whatsoever in the set.