I doubt anybody will create diablo clone template for marketplace. There are already modules that when put together could make such game. Catch is that even if you had them all, there would be some serious coding involved before everything could work together. Also unless you are looking for ready to use diablo template (together with menus spells, proceduraly generated levels, and all that) you will need to code anyway. There is just no escape from coding if you want to make game, you need to learn blueprints soon or later.
Saying that, there is top down template, which is great start for diablo. Then there are infinity blade assets for tiles, enemies, weapons. And “Dungeon Architect” plugin that can make procedural levels. Granted i knew what i was doing, but i could put it all together in one weekend (of which most time was making theme for dungeon architect).
So get dungeon architect, get those assets, and make testing level. Dungeon architect has example themes for infinity blade assets, and has nice documentation. When you are more familiar with blueprints there are packages for weapons inventory, spells, etc.
I write once more: i doubt anybody will make whole diablo game to sell on marketplace, it is a lot of work, and not many potential customers. Making bigger pack (like all that game functionality in one package) is lots of work and on top of that limits potential customers number, it is better to make few smaller modules that cover smaller aspects.