Like Zendikar or Kamigawa?

Mercadia, Ulgrotha, lots of possibilities.

(The "primarily" in the challenge gives rather more leeway; Fiora might count even though its most prominent cards are multicolour legends and artifact creatures; heck, even Ravnica probably has more than 50% of the cards set there as monocolour. But I think the intended spirit is "choose a setting with few or no gold cards and make a gold card for it".)

I made Moonlit Savior, from Kamigawa, of course.

I wanted more constraints, so I asked random.org to combine this with another challenge, getting Challenge # 017. Created Hunter's Contempt (from Lorwyn) based on that constraint and this.

Then combining this with Challenge # 097, I created Kami of Devastation, also from Kamigawa.

I made Roiling Coiler, by the way. It's from Zendikar.

Rolling again, I hit Challenge # 031. Um... I've already used that in a mashup multichallenge for Challenge # 073, and it's rather hard work. Since I'm doing this for fun I'm going to reroll. Rerolling I get Challenge # 112... I don't think those two are really compatible. It's asking for a card for Lorwyn, Zendikar, Theros or whatever, that also fits Danahar. Many cards are setting-neutral, like Lightning Strike or Giant Growth; combining these two challenges to get one of those is a very boring option. Is it possible to make something that's a specific flavour that fits either Danahar or a real monocoloured plane? I spent a while looking, but couldn't think of anything.

So rolling one more time, I got Challenge # 081. Okay, that we can do. A gold charm for a mono-colour plane. Not costing any simple CD or CDE combination as Ravnica, Alara and Tarkir took those.

I wanted to revisit Mercadia, so I narrowed my thinking down to two-colour charms themed around some of the factions from Mercadia, aiming for effects that cost more than 2 to get above the costs of the Ravnica charms. I ended up creating Kyren Charm and Rishadan Charm.

What a cool challenge. I've got some pre-designed ones: Sigarda's Assistance and Avacynian Cathar. I think both could have fit Innistrad's block quite well with the token theme and flickering.

Added Punify.

Since Kamigawa is sorely lacking in commander material, I made Black-Nose.