5how to get the set
Nothing drops this and nothing crafts it. Find an Oasis in a surface desert, stand at the pool and throw a Platinum Coin into the water, and the outfit comes back up. It costs money rather than a fight, so it is available at any stage of a run as soon as you can gather the coin and reach a desert. The Hat, Coat and Pants all sit in social slots.
the extras that come with it
The clothing is not everything the pool gives up. A pair of wings arrives in a dormant state and has to be crafted into Heroicis' Wings before it will lift you, so do not write them off as another vanity piece. The Film Projector comes too, which is a monolith you place in a base to tint the screen for anyone standing near it.
where it came from
The set exists because of a Make-a-Wish partnership with a seventeen year old named Frank, whose handle was Heroicis. Throwing a coin into water to receive it is a wishing well joke pointed straight at that origin. The lines written on each piece are loose rewrites of things Iroh says in Avatar: The Last Airbender.