Hm. This seemed an obvious idea, but the templating doesn't really fit. Is there any way of avoiding X, avoiding saying "the damage" and "that creature" multiple times, and allowing searching only for auras which can enchant the creature?

(I've also made "witch" a creature type, which is non-politically-correct, but more flavourful than leaving them all as wizards or shamans.)

I think this still lets you attach "Enchant land" and "Enchant artifact" to it, too. And 'then shuffle' still isn't part of search. And yeah, this is gonna end up flyspeck 2, no matter what you try I fear.

Mayyybe something like the very non-canon wording:

You may search-reveal-shuffle your library for an aura whenever ~ is damaged by a creature. If the aura may legally enchant ~ and has CMC equal to the damage dealt put it into play attached to ~, otherwise discard it.

Also: "Witches" used to be a creature type. So go for it. (Original Cuombajj Witches print)

and now I'm already imagining the FAQ for that wording. "But I've got stuff in play that makes everything an artifact! And another thing giving artifacts shroud! But it's coming into play, so it doesn't target, so that's ok now, right? And I gave it protection from black, but the aura isn't black, so is it the effect or the aura that matters?"

"Whenever a creature deals damage to ~, you may search your library for an Aura card that could enchant that creature with converted mana cost X, where X is the amount of damage dealt to ~. Put it onto the battlefield attached to that creature, then shuffle your library." That's not so bad. I got the wording off of Sovereigns of Lost Alara.