That art! And this is a rare open for any kind of Angel design, really.
So this lady is smiling, and it reminded me of peacefulness, so I thought of doing something like Holy Day. Or, better yet, like the rules text of Empty City Ruse. It's preventing from creatures from even attacking in the first place. That's more appropriate for peacefulness - not preventing damage. Because creatures are still able to attack anyway. Doesn't feel right.
I also like it when Angels "save the day," as they should. Serenity Seraph here (I actually wanted to call this Serenity Angel, but Angel of Serenity already exists, and that would be confusing) makes sure you at least have a chance to attack with her before you die to creatures if this Angel was supposed to be your saving grace.