Sorry for my ignorance, but what is list building comps?
So I set a challenge -say build the best 2,000pt Ulthwe list.
We all get a couple of weeks to post & refine our lists.
Then Irisado posts a poll, and we vote on the winner.
We did maybe a dozen of them during 7th ed. It was pretty good fun, and prompted quite a few interesting discussions around unit efficiency, tactics, and fluff.
Some of the lists even made it to the table.